What do you mean by angles of attack and strut settings?

I figured that going light would help - the same applies to most things (cars - airboats - planes)
the frame is very light - 3/16 balsa skinned with 1/32 plywood. The transome is 1/4" plywood.

Should I really make the sponson insudes out of foam (the pink stuff?) if so, should I use it anywhere else in the boat?

Thank you for your informative answers!