For those that haven't been following my saga, I'm a newbie taking an adult
ed class. I've chosen to make a bookcase for my project.

So I have all of my pieces cut to size and am ready to put it all together.
I plan on using woodscrews to attach the pieces. I'm also planning on
"sinking the screw head into a larger hole" (not sure what to call that) cut
with a forstener bit and cutting my own plugs to fill in the hole. So now
on to the questions...

1) What size forstener bit should I use (knowing I need to match the plug
cutter)? Most of the panels are 3/4" x 10.5" x differing lengths.

2) How deep should I cut the forstener "hole"?

3) Sanding - should I sand all my pieces before attaching the pieces with
the screws? I ask because I know I'm going to have some additional sanding
after cutting the plugs off in the screw holes. So do I sand everything
first and then just re-sand the plug areas? Or do I wait and not sand until
the plugs are in?

If it makes any difference, I'm going to need to do some evening on the
panels I glued together (there is a little variation here and there that I
need to make flat) - either with heaving sanding or trying to hand plane to
flat.

Thanks for the advice.