Your valve question has been answered (BTW skull, you forgot the butt exhaust ).
I use latex seals. My experience is they provide a little better seal and you don't need the noeprene to keep you warm in the caves.
I will also suggest you get a crushed neoprene suit. IMO it holds its form better and prevents a lot of the problems of air movement that you get with trilam. I'm sure this has just opened up a whole new can, but I think, given the choice and having the money, most would choose crushed neoprene.
I use latex seals. My experience is they provide a little better seal and you don't need the noeprene to keep you warm in the caves.
I will also suggest you get a crushed neoprene suit. IMO it holds its form better and prevents a lot of the problems of air movement that you get with trilam. I'm sure this has just opened up a whole new can, but I think, given the choice and having the money, most would choose crushed neoprene.