The line is spaced about 1/16" apart and 3/16" from the hinge line. There is plenty of meat there to hold the elevator on, and the threads themselves have a huge margin of overstrength. The number of loops is based on the balsa strength, not the thread. I suspect two loops would suffice, but 4 in several locations doesn't cause any binding, so why not.
Figure eitht hinges have been outlined elsewhere, so do a search. Basically, you run a needle and thread through one surface, pull it to near the end, glue the end. Then up through the hinge joint and down through the other surface, up through the joint and down through the original surface. Viewed from the side it forms a figure eight of threads. When you have 3 or 4 eights, tighten up the thread, level the two surfaces and glue all the penetration points top and bottom, but not the thread where it goes between the surfaces.
Definitely my favorite hinge for 1/2A.