I'm still pregnant (and hoping for that VBAC) but after my c/s last time there were a few things...
The mesh panties really are amazingly comfy, but the high belly grannie undies worked too (I'm a low cut bikini type and ALL my regular unders hit the line...ugh). I sent DH to target to buy plain old white undies in a huge size and then I cut through the elastic of the waistband so they stayed on but had no real "pressure". And I didn't feel bad about throwing them out later.
I also had DH buy a "toilet topper" from a local pharmacy. You can find them in the "geriatric" section usually...they are essentially a tube of plastic that sit on top of the toilet seat and raise the level of the toilet. I found that the bending/squatting motion of getting down onto and then back up off of the toilet was just horrible...and the toilet topper is designed to help people with that sort of mobility issue. I used it for about a week and it was the best 20 bucks I ever spent.
If your surgeon didn't send you home with information about scar massage call them! Or check out the info in the "Natural Family Living Cesarean Support" sticky at the top of the Birth and Beyond forum. It's my pet peeve about c/s actually. Scar massage is free, easy to do, and can speed healing, reduce or even prevent adhesions, and stimulate nerve healing. Just about everyone I know who has had surgery has been told about or instructed in scar massage...but no one mentions it after a c/s! Basically, once the staples are removed or the sutures dissolve (give it a week or two) you can start doing scar massage. There is a whole chapter on it in the post-partum exercise book "Bounce Back after the Baby" (the author had a c/s) and links to "how to" info in the Birth & Beyond sticky.
I had really bad constipation after my c/s. Although I kept taking the colace and gas-x and doing all that eventually I turned to the "traditional" mineral oil cure. This isn't a terribly healthy cure, and you shouldn't use it more than a day or two, but it works!

Basically, you make up some chocolate pudding and add a few tablespoons of mineral oil to the pudding. Then eat a bowl. I think I had 2 bowls the first day, and 2 bowls the second, and then it wasn't an issue anymore! The mineral oil will pull vitamins/nutrients out of you though so as I said, it's not a good idea to use frequently, and make sure you're taking a good supplement. But after 5 days I was desperate...
Hang in there mamas...healing from a c/s is tough work, especially with a toddler or older kiddos on top of the new babe...so make sure you pamper yourself as much as possible and cut yourself A LOT of slack in terms of what you "need" to do. Eat a few yummy chocolates, have a glass of something you enjoy, let your older kiddos watch yet another video or more tv than they usually get, ignore the cleaning/dishes/whatever and just focus on healing up and loving that babe!