I'm so glad to see this is taking shape. I'm watching from the sidelines!
I was looking into hotel reservations before I found out I could not make it. I don't think you need to pay upfront for the hotel rooms. The only thing you need to reserve a block of rooms is ONE credit card on file, and as people check in, the front desk will change the reservation to the credit card of the person taking the room.
IMPORTANT: Don't use a banking/ ATM card with a CC logo on it. If you use one, the hotel will deduct the stay upfront.
As long as you cancel any "leftover" rooms before the cancellation period - usually 24 hrs - the hotel bill becomes the responsibility of the person taking each room.