If you're going to FG the center section, then by all means, epoxy the two halve together.

As for the Fiberglass, Here's what I do:

Spray the wing LIGHTLY with a spray adheasive then, tack the cloth down to the wing. Next, wet the cloth with THIN CA (You can use medium, but you'll have to rub it into the weave with some waxed paper). Whichever you use, do it outdoors! It will create tons of fumes!