Outgassing is very real, but very controllable. You can even make it work to your advantage.

After much worry and trepidation I took a beautiful weather long weekend and glassed my hull. I did what I was told, in that I waited until after peak afternoon heat, and started glassing as it cooled. There are no bubbles in my hull. None, nada, zip, zero, not there. And just like a lot of people told me, it really sucked the glass cloth down hard against the hull. I was also done in about 2 or so. Scouts honor, this was about the easiest part of the whole boat building project! I was astonished at how easily this job went. So no, you do not inherently get a funky looking glass job if you don't seal coat the wood.

I cannot adequately answer your question about the mechanical bonding properties of a second coat of epoxy over a fully cured lower coat. There are many variables, particularly the abrasion of the lower surface. I can give you an example, but I can't put numbers to it.

I once split a set of abs plastic motorcycle bags to expand them with a polyester resin bondo kit (hey, all I knew was cars, what can I say). I beveled the edges of the plastic, and sanded it up to get a roughed surface. Probably a medium grit sandpaper. I made the bags wider, and then ripped them apart by hand testing them. Very disapointing. I again attacked the plastic, this time widening the bevel and and severely abrading the surface, using everything from a wire brush to a cheese grater to the coarsest sand paper I could get. I did not clean up the surface at all, but left it as horrible looking as I could. Reglassed. Those bags went through thousands of miles carrying upwards of 100 lbs in each, bouncing over the nastiest New England logging trails, being filled with tool boxes and other such hard heavy items, and enduring several spills. They never failed in the years I had them. To this day, I really regret ever letting them go.