To answer the bit about theme park tickets first, I normally buy them here before I go, and they seem to arrive about 10 days from when ordered, so you have plenty of time between now and March 2007.

I'm not sure when will be the cheapest time to book, but I think if you want dates that fit in with the 2 weeks that our schools here are on their easter holidays, it's best to book sooner rather than later. My understanding is that Easter is one of the busiest times in Orlando.

One year I was restricted on the dates that I could fly out at Easter and was having such problems getting a booking I ended up going in the summer hols instead.