> A Couple of questions, What is the best way to (a)fasten the seat in until
> I find the best position(using mincell foam)? (b) the best way to
> permanently fasten the seat in?

Double-sticky carpet tape makes a pretty good non-permanent means of holding the seat in place. Contact cement is a good permanent adheasive.

> I'm using 2" closed cell foam for the bulkheads, what are some of the
> popular sealers/adhesives used to secure and seal them?

3M 5200 is hard too beat. Regular Silicone sealant (RTV) is pretty good but may fail after a while.