we bought our first AP's when our kids were 9yo, 3yo, and 5 months old. we continued to go at least weekly (sometimes 2 or 3 times per week) for the following 2 years unless we were blocked out. so, my youngest daughter spent a LOT of her first few years of life at DLR.
the only thing that ever really concerned me was germs, lol. my kids were SUPER easy to manage at the parks, despite the fact that the baby wouldn't sleep AT ALL while we were there. we just held her on our laps (before they got strict with the no lap-sitting rule) for any ride she was allowed to go on.
we always did (and still do) incorporate a lot of hand washing, etc. into our time at the parks to try to avoid illness. the only thing my kids ever (apparently) caught there was the chicken pox, and that was when they were all older. although, that would be a major concern for a newborn (unless you're breastfeeding and you are yourself immune? if that's the case, the baby should be protected).
in regards to breastfeeding, i always found it easy to nurse in the parks (but we were usually only in the parks for 3-5 hours each time we went - it might be more draining if you had to do it all day, for multiple days).
personally, i would be WAY too physically affected by childbirth to take a baby who is just a couple of weeks old. i don't take my newborns out into public until they are at least 6 weeks old though, either. you might want to re-think your timing....
disneyland is a TON of walking. i know for myself, i could never have handled that kind of physical exertion that soon (and it's not really good for you - your body needs a good 4-6 weeks to really heal). also, if the baby arrives later than you're thinking, one thing to keep in mind is that nursing is pretty uncomfortable for the first 2 weeks (downright painful at times), and that is NOTHING that i personally would want to deal with while at disneyland, either.
just some food for thought! congrats on your soon-to-be new arrival!