Well I can answer this for you, even though I don't have a little one. I've been to Disney a number of times with and without little ones so I've learned a lot and my cousin used to work at Disney World so she's provided a lot of information as well.
Each park that you visit has baby care centers. It's places that you can go to nurse, change diapers, feed babies and buy any essentials that you may have forgotten or lost. You can also warm bottles, etc. there so just make sure to locate the nearest center so that you can find it easily when you are in need of it.
As far as her snacks go, bring them with you to the parks and let her munch them whenever she's wanting them. Disney does NOT care if Rayanne or any other baby spreads puffs from one end of the park to another, just as long as she's enjoying herself.

She can eat them as you walk from attraction to attraction, while you wait in line or are watching a show or when you are standing there waiting for the parade to start. You can also bring along bottled water and snacks for yourselves as well, just don't bring in a whole picnic lunch.
This link will show you pictures of what one of the baby care centers looks like and as you can see, it's pretty much a full service baby area.
Baby Care Facilities (in the parks)
As far as flying goes, I don't know if you know this or not but I saw someone else mention it here, just make sure to nurse her or give her a bottle (can't remember which she takes) during take off to help minimize her ears popping. Anything else about flying with a baby will have to be told to you by others. LOL
Yall have a great time when you go! I love Disney, it's AWESOME!!!