Well to start

Stringer- They look like a half a paper towel roll on the inside of the hull. It provides stiffness to the hull so that it isn't just a sheet of fiberglass. If it has ports looks about half way up the hull.

Bulkhead- These should be around where the cross bars connect, it is a vertical piece of fiberglass perpendicular to the hull that provides support, you can reach past them except under where the water can run.

Diamond Wires- The wires that form a diamond like shape on the mast, you called them mast tensioners. They are used to control the bend of the mast, and can be used to intiate prebend. Starting out...just make sure they are there.

I will try and get some pictures soon.