Ergos are awesome, and I used mine constantly from 4 months on with my son, and still wear him on my back sometimes. But for a newborn I would highly recommend a wrap. I prefer the moby wrap. It evenly distributes the weight of the baby and I find I can carry her longer in a moby wrap, and it's also easier for her to sleep in, since I can cover her head one she falls asleep with the extra fabric. I would really invest in one, as I don't know how I would get by without being able to pop my daughter in the wrap so I could take care of my son. This is the ONLY way I feel safe bringing both kids out to the car in the snow or up or down stairs. With her in the moby and holding my toddlers hand, I feel confident on the stairs. So that would be my recommendation. And I also can chase my toddler pretty well if my daughter is secured in the wrap, so I would try that and see if it helps you get outside more. I wish I lived someplace warmer. Upstate NY makes it REALLY difficult to get both kids outside in January (it's 15 degrees here with gusting winds...brrr).
Toddlers are little sponges and they learn from EVERYTHING. Just watching you do everyday activities has him learning, so don't feel like you're "behind". But here are some activities I do with my son:
color/draw (we have a chalkboard, whiteboard, and paper with crayons and markers. This is a great way to introduce colors and shapes and even animals if your artistically inclined. And it's fun for mom and toddler)*
do puzzles (get an age appropriate puzzle with animals or shapes and introduce the names of each. This is how Wyatt learned his animal sounds, because I'd make the sound as he did the animal puzzle.)
read books (position the toddler next to you on the bed or couch and hold/nurse the newborn with one hand while turning the pages with the other)
yoga/stretching (this is great for one on one time! Wyatt has a blast stretching with me.)
chasing around the house (Again, I mainly do this when my husband is home so I don't have to worry about the baby. And I just chase him and let him climb under the blankets and tickle him and blow raspberries on his belly and he giggles and it gets me some exercise :)
Activities he'll do on his own (I have a VERY independent toddler who likes to play by himself):
Play with his trains/trucks/cars (we have a train table with tracks set up and he'll play at that by himself for 30 minutes easy)
Pour with beans (give him different containers and some dry beans to pour. It makes a bit of a mess, but if you use large beans like kidney or lima beans it's pretty easy to clean up)
Play in the sink (we're getting him a water table for his birthday because he is SO into water play. He will sit at the sink and pour water all day)
Play with a box (seriously, an empty box will keep my kid occupied! Especially a big box that he can sit in and I can pull him around the room in.)
There's also a few things I keep on "reserve" for when I really need a break so they're extra special and I know he'll keep busy with them for a few minutes. They include:
His own wallet- we have an old wallet filled with old credit/gift cards and a few coins and if I give him that he will play with it for awhile. I don't keep it with the normal toys, so it's a special toy he gets to play with when I need him to occupy himself and nothing else is working
Watching Charlie and Lola DVDs- we're a no TV house, but I started taking out DVDs from the library to play on the computer for Wyatt when I need to spend some one on one time with the baby. And the DVDs definitely do the trick!
I also always have him help me with chores, so he has his own little broom and "sweeps" when I sweep, as well as a mini vacuum to vacuum with when I do, and he also "helps" with laundry (he can match socks now, and he also helps move the clothes from washer to dryer) and he feeds the dog every morning. He'll also get things for me for the baby while I'm nursing, like burp clothes, blankets, or pacifiers that I keep within his reach. Which I think helps him feel involved. Wyatt also takes a bath every day, because he LOVES bath time and I can just sit while he plays and either take care of Emma or just sit, which I need to do some days. He spends 30+ minutes in the bath everyday before bed.
We're also very involved outside of the house. So we go to a playgroup once or twice a week (at friend's houses or hosted here), the museum, or an indoor play place (we're lucky and have some great play places here like http://www.thesandboxplayground.com/), and we try to take a walk every morning with the dog (when it's not terribly cold like today). I walk the dog, with Wyatt in the stroller and Emma in the moby, and that works out pretty well.