jdoyle,
I too am building a 4* 60. As far as the hinges are concerned, CA hinges provided are plenty good enough.

The straight pins in the hinges, as shown, is to ensure that there is enough space between the wing, horiz stab, or vert stab and the control surface so that they don't bind after everything is glued together.

Drill a 3/32" hole 1/4 to 1/2" deep in the center of each slot on the wing, stabs, and also in the center of the slot in the control surface you are gluing to it. The CA will wick into the slot and the hinges much better that way, ensuring a good bond.

You can go ahead and cover the space left after the hinges are glued into place but, I don't think you will have a problem with flutter as the aircraft really isn't that fast. You can do it if you want, I'm not going to do mine.

I am also building a Great Planes Shoestring. It will be powered by an OS91FX and will fliy fast enough for flutter to be a concern. I intend to use high torque servos as a preventative measure.

Good luck with it. Keep us posted on your progress.

doubledee