Angela,
I strongly suggest that you bring your own stroller, or make arrangements to rent a stroller off site. The strollers available for rental on Disney property are not suitable for an infant, do not recline, and would not be very comfortable for a nap. They are hard plastic, not a cushioned seat like traditional strollers. (For a visual, check out
www.allears.net and search 'strollers'. The first search result has detailed information and photos of the strollers available for rent in the parks.)
The Animal Kingdom Lodge is a fantastic resort! There will be bus service from the resort to all of the theme parks and Downtown Disney. Allow yourself a little extra time when using the buses and you should be just fine. If you are really in a pinch, taxis are also readily available at the resort and parks.
You don't mention what time of year you are visiting, but if it's in hot weather I recommend a battery powered clip on fan to keep your little one cool in the stroller. A rain cover is also very nice for keeping the stroller dry. And when my girls were little, I liked to pack their clothes in ziploc bags. I'd place one outfit in each, which helped to keep the suitcase organized, made it easier for my husband to grab a bag and dress the kids, and also gave me a nice storage spot for wet/dirty clothes later in the day. It's also very easy to grab a bag of spare clothes and toss in the stroller for your day in the parks.
Hope that helps!