At the beginning of your post I felt my lip begin to twitch. But then I got to the part where you were going to foster for a shelter and I suddenly got that happy, fuzzy feeling.

Depending on the dog (size, breed, etc) the space requirements for a whelping box can be as small as an over sized rubbermaid bin, to a large wooden box with safety rails that can literally take up a whole room.
You'll definitely need a place where the bitch can be comfortable before the pups are born. Many people assemble their boxes long before their due dates and let the dog get comfortable. If you have kids it's probably best to have this in a place that can easily be closed up when needed. Even though the intent is to socialize the pups, you'll still need a place where she can feel relaxed and secure. And, where you can feel comfortable knowing that well meaning children won't be trying to handle newborn puppies without your supervision. (I'm not sure how old your kids are.)
If they're coming from a shelter, do you know what their procedures are as far as vet care for the dog goes? Do they perform ultrasounds or x-rays to see how many pups there might be? What about possible c-sections? Etc?
It might be nice to know what the shelter provides, and then we can sort of fill in the rest.
I already mentioned a whelping box. For delivery, you're going to want to line it with something absorbent and easily changeable. Don't use something big, like a full sized blanket. It's best to use several small pieces, like towels, that can easily be changed out without disrupting the whole box. Different people like different things. I've used everything from layers of blank news print (like packing paper) and piddle pads, to towels and scrap fabric. It's best not have fluffy thick fabrics that the pups can get lost in. And I don't recommend shavings, especially ceder. It can be inhaled, chewed/choked on, and ceder is really hard on their respiratory systems.
You'll need a whelping kit. The list of stuff is endless, but anything and everything that you might think will help you is important to add. I would say the major things would be this:
Note pad, pen/pencil (recording birth weights)
Scale (weigh newborn pups)
Hemostats (clamping cords)
Scissors
Iodine (umbilical cords)
Dental floss (tying cords)
Bulb syringe
Lots of fresh towels
Different colours of embroidery thread or yarn (colour code each pup for identification)
Thermometer
Rubber gloves
Lubricant (in case you have to insert a hand or finger)
Depending on the breed, and therefore the size of the pups, you may need some sort of heating system, either a lamp or pad. Usually though, if you control the ambient temperature and take measures to ensure the box is not chilled (like not placing it directly on a concrete floor in the basement, for example), you should be Ok.
If the dog has long hair you may want to trim up her bloomer hair and on her belly. Some dogs will shed a bit around their nipples though. Some waterless bath and a slicker brush might be handy to help clean her up after. You may also want to consider having some milk replacer and feeding supplies on hand just in case. Pet supply stores won't be open in the middle of the night and if a pup won't nurse or the bitch won't let them, several hours can be difference between life and death. You'll also want to think about what to feed mama after labor (though she might not want to eat right away). If you feed raw it will be a good time to offer some organ meat (liver especially), or some egg yolks. Both are good sources of iron. If not you could cook them add them to a high quality kibble. If she eats a lot of the placentas, she might have diarrhea for a couple of days. Even though you'd typically want to offer a bland diet for a dog with diarrhea, you sort of have to roll with the punches here because you really want to get her milk supply off to a good start. Food and drinking lots of water are really important.
The first couple of days are really important, so be prepared to sleep near the pups and set an alarm to check on the several times if needed. They'll need to be weighed daily. And you may have to walk the dog several times a day if she won't leave the box. Sometimes it takes having her out of the box to eat too, so be prepared to spend all day with the dog or the pups for the first week or so.
Around 3-4 weeks is really when they start to get mobile and open their eyes, and this is when they'll be ready for the kids to start with handling them. They'll also start getting weaned around this time (closer to 4 probably), so you'll have to start incorporating puppy meals. There are lots of good recipes out there for a puppy mash.
4 weeks on is when they really start to learn a lot from each other and from the bitch. You'll notice she probably wants to start spending less time with them, and when she does, she's not as nurturing and tolerate. This is a GOOD thing. When we keep saying it's important for puppies to stay with their litter mates and go through the process of being weaned by their mother, it's because of this. They learn things like bite inhibition and other manners. When puppies are removed too early they often have a hard time understanding what is appropriate and that can lead to things like them being really mouthy.
You may want to invest in an outdoor exercise pen. Even if you have a fenced yard they're handy because they keep the puppies contained to a small area. If you have 6 puppies all scattering in opposite directions and one or more of them gets into something, you'll be pulling your hair out.
Now's the time you may also have think about moving them out of the whelping box and into somewhere more secure. You can use the above mentioned "x-pen" indoors, or gate off a laundry room or kitchen. Be prepared to clean a lot of messes. You can paper train them, or shall I say, use paper to contain the messes, but usually paper and piddle pads aren't recommended because the puppies can chew it up and you don't want them eating that stuff. Especially piddle pads. Blank news print or towels are probably your best bet.
Don't hesitate to start pottying them as early as they can walk outside on a leash. Like 5-7 weeks. It's time consuming, but it lays the ground work for later. It would be difficult to simultaneously potty train 6 pups all at once at such a young age, but it's also not recommended to let them have a free for all in side the house either. Not keeping their area clean can lead to things like coprophagia. They'll need to go outside to potty every hour as they get to be around 5-8 weeks.
Realistically, expect those 12-14 weeks (including the sleepless week or so before she whelps) to be exhausting, draining, frustrating, messy, disgusting, confusing, mind boggling, and totally fulfilling (if you enjoy the experience, but you won't know that until it's over.. LOL).
Are your kids at an age where if you hear a puppy screaming you can drop EVERYTHING (or have help) and go attend to the pup? Are you willing to bath a whole litter of pups if you wake up in the morning and they've been tromping around in poop? If mama's labor stalls, are you able to leave in the middle of the night to take her to the vet? If the shelter doesn't pay for it, can you afford it? Are you willing to make huge sacrifices and alternations to your home so you can accommodate a litter of puppies for 12 weeks? Like putting up baby gates, or moving furniture around, or removing carpet, or fencing your yard? What about the expense of building a whelping box, buying milk replacer and bottles and nipples, x-pens, crates, extra towels, food, puppy toys, etc?
I won't lie. Having puppies is so incredibly rewarding. And they are flipping adorable. But. BUT. They are also a tremendous amount of work. And not unlike having a human baby, in those first couple of weeks everything is sort of a blur. You need to be at a place where you're comfortable setting your kids up with a movie or activities while you clean out the whelping box and sterilize the floors (if they're not old enough to help). Or have someone come in to help you.
I have not raised a litter of pups since I had my daughter, truthfully, because I just don't think I can do it. She's 4 now, so it's probably do-able. But I sometimes find myself getting exasperated with the dogs I have now. Caring for young puppies and all the stuff that goes along with it is down right tiring at times.
I would suggest you get in touch with other foster homes, or a breeder, and volunteer to spend a day with them, or a few days, do some of the hands on work and see if it's something you can do in your own home. Once you have that dog in there a new litter of pups, you're sort of obligated to go through with it all. That's not the right time to find out that you're totally overwhelmed and can't keep going. I REALLY suggest shadowing someone with litter of pups first.
It also sounds like you don't have a dog, and possibly don't know what it's like owning a dog? I'm not sure if the shelter will consider you a good foster home due to lack of experience, but if they do, it might also be worth doing some volunteer time at the shelter. Raising a litter of pups with a strange dog is going to be night and day to taking in one older puppy/dog. If your goal is to find out whether or not you want to own a dog, sign up to be a foster for one dog, get some experience as canine caretaker, and then take on the litter of pups.
Honestly, it sounds like you're putting the cart before the horse, and I'm not sure this is the best way to figure out if dog ownership is something you're interested in.
You mention that it would be a good experience for you and your daughter, but I wonder what other reasons have motivated you to foster a litter of pups? Foster homes are needed because shelters are over crowded and small pups don't always get the one-on-one time they need for socializing. And because wasting space for non-adoptable dogs for 8-12 weeks takes away space for dogs in critical need of finding homes. And because shelters honestly don't have the time needed to raise a litter of puppies. They would have to have staff members specifically on puppy duty, and at the shelters I volunteered for, that was a huge issue for us. It's SO time consuming that we much prefer foster homes.
The experience of raising pups really is unique, but I do question your motives for wanting to go through with it. If it's really to have a "test run" before owning your own dog, there are foster programs that place one dog. And if you want to experience caring for puppies, volunteering before becoming a foster home (and I would recommend you gain some experience before taking it on yourself) might be better.
I'm sure I've forgotten a ton. It's late, but I'm sure others will chime in. Time for bed. LOL