Yes, there are elevators in the mansions. We stayed in Magnolia Terrace (which is non-smoking) and it was right next to one of the bus stops. I don't think any of the mansions are really close to the food court, but Oak Manor is closest (but is a smoking building), followed closely by Magnolia Terrace. It's about a 5 minute walk (much longer if your 2 year old also walks).
We stayed there with our 18 month old 2 years ago and found it easiest to put him in the stroller in the morning when we were in a hurry. When we were back for our afternoon break, we let him walk and explore Old Man Island (where the pool & playground are). Old Man Island is also very close to Magnolia Terrace.
We were on the second floor (standard view), so I can't answer your first floor question. I will comment that the second floor was very quiet.
Enjoy it. It is a nice place to stay.