1. Decide all your dinner places now and call now and book them all. You can possibly make changes later but get something in place to assure you will have a place to eat.
2. Do not go to MK on Easter Sunday. Absolutely nothing happens there on Easter that you cannot see other days of the week. However, 80% of the visitors to WDW at Easter don't know that and they ALL go to MK on Easter because they think something is going to happen there on Easter that they cannot see other days.
3. Epcot, MGM and AK have their lightest days of the holiday period on Easter and day before (note that is relative and light just means better than "it is so crowded I can't even breath" which it is like most of the time). MK has nothing during the entire holiday period that one could even consider "lighter" but Easter Sunday and day after are the worst.
4. The second Fantasmic at night is a walk-in just before show-time. For the first, you need to line up almost an hour early just to get in.
5. Best time to try to get on the big rides without fastpass -- first thing in the morning when a park opens (and they often open earlier than usual during Easter time). Fastpasses for entire day and evening often run out by 11:30 a.m. for those popular ones, and stand-by lines for Test Track and Soarin can get to three hours and the mountains go to well over two and stay there.
6. If you want to do a water park, plan to be there when it opens if you want a chair; plan to be there before 11 (or after 3) if you want to get in at all.