Hey mitty, You can get these type of hinges in two or three flavors , small-1/2A thru .20 size, medeum-.40 thru .60, large- .60 thru as big as you dare. On my 80" span Pipe Dream I have the large type spaced 8" apart but would have liked them 6" apart but didnt have more on hand and didnt want to make the 20 mile plus drive to the hobby store. At 8" they work fine but a few more isnt going to hurt anything. On each flying surface, make sure your hinges are within a 1/2 inch or so from the end of the flying surface. Makes a stronger hingeline by dampening vibrations better.

A CA hinge is one that is made from a fiberglass type matting thats paper thin. Just slit the balsa, insert the hinge and add a drop of thin CA, it wicks its way into the matte and balsa securing it.
There fine for most planes but i had a Goldberg Eagle 63 that I used them in and after four sesons of flying they started to tear down the crease line. Ever take a peice of metal or plastic and bend it back and forth untill it broke? thats what will happen sooner or later with this type of hinging. the ca glue stiffins the matte and as it bends it tears the tiny fibers of the matte. The larger the surface diflection the faster failure will happen. On small, lightweight models, might last forever. Larger models....dont bank on it. Piper