Does anyone know how far in advance I need to make a reservation here? Do I have to pay in full when making the reservation? Not going until June/July 2008

You don't have to pay in advance. You can book 180 days out, and I would call as soon as possible since the summer months are busy. You can cancel a few days ahead with no penalty, so it's probably better to book early and get your choice of times.

That said, I have been able to get reservations just a month or two ahead of time -- once in the off-season, once in the spring. The last time, we had to take the late seating, which was fine because it worked better with our schedule.

It's a great experience! Enjoy!