E.P.
Love Disneyworld! My family and I have been there over a dozen times and we do not tire of it! My son was 5 months old and my daughter was 3 1/2 years on their first trip. If you can afford it - they are not too young!
You may try looking into a moderate resort - our favorite is Coronado Springs but many people like Carribbean Beach. Animal Lodge is very cool but very dark colors. I feel you can get the same feel for the safari by going to animal kingdom.
Good deals can be found at Disney - just go to their website. If you want more information from me, I certainly could overwhelm you with some and I don't want to do that because it is early in your planning. Feel free to personal message me should you have more questions. Good luck.