I was there in MD 2006. It was really hot to the point I though my shoes where melting, but, I was 7 months pregnant then and my feet were swollen, so maybe that is not of help to you.
Now on the crows, in my opinion there were more people than on thanksgiving weekend, which we did on 05. I was at the park either very early in the morning or in the late afternoon, so I imagine that during midday hours the amount of people was worst. We spent most of our afternoons on the pool of BWV, which was packed. They were handing bracelets to make sure no one else but those staying at the hotel were in the premises, and still there was not a chair to be found.
We stayed for the entire week, not only the weekend, and I think many schools in florida end classes around that time, so maybe that was the reason of the extra packed park. Probably the week before MD is quieter, but the weekend itself - lots of people.
HIH