At regionals, they will almost certainly have actual Toobers for modeling. If they don't, well, then there's something wrong, since it's not like an invite, which is just practice. The major invites like Solon and Mentor will also probably have Toobers, but some of the less commonly-attended ones might not, and you'll have to deal with that. It actually might be good practice to have to deal with something that doesn't hold its shape as well.
I think it is necessary to have 3. You have to deal with both the test and the model at the same time, and in order to model the protein quickly, sometimes you have to have 2 people working together. Then, the third person can work on the test, and if there's time, the you can go over the test together and tweak your model. I think, with only 2 people, they would both have to be very strong (and be able to work independently) in the event, otherwise you may run out of time trying to focus on one part and not the other.
I don't know about textbooks personally. Phenyl might have suggestions, but I'd just say that an AP Bio book might be helpful with regards to general protein information. Other than that, the Internet is your friend.




