I just booked for the same week! This will be our first stay at the fort, so I can't help with that, but we were there the first week of April this year and it was by far my favorite time to go compared to June and November. The weather was wonderful. We had a few days in the 90's where it was hot if you were in direct sun, but we are afternoon break people so that didn't affect us too much. Even then it's a normal amount of humidity versus that Africa-hot-wall-of-heat that hits you during the summer. It was warm enough in the morning that we didn't have to wear sweatshirts, so we didn't get stuck carrying them around later in the day like in November. (One night we wished we had brought them to see Wishes, but otherwise never needed them, it stays warm so late there.) I had heard so much about "Easter crowds" that I was really nervous, but it didn't feel any busier than summer to me. We followed
www.easywdw.com's recommended days and didn't have a problem with crowds. MK opens as early as 7 am the two weeks surrounding Easter and those are such nice touring days. (We walked on Dumbo several times in a row with no wait, how often does that happen?!) The parks do get VERY crowded in the afternoon and evening so if your crew can handle early mornings you're better off doing those than late nights. We are hoping to do a fireworks cruise or watch Wishes from FW beach for this trip to avoid some of the late night crowds at MK.
I'm interested to see if others can chime in about the fort. I think there's an easter egg hunt maybe?