I need some advice about a pneumatic brad nailer. I've never had one,
and they look like they would be a real help when the guys on TV use
them. Question #1: Is an eighteen gauge nailer what I want? I will be
building a bookcase/desk out of ¾” plywood (to be painted) and I'll be
using the nailer to attach trim around the top, and to put on the
backs of the bookcases (½” plywood). Not sure just yet if I will use
it for the shelves, but I'm pretty sure I won't – they will probably
be adjustable.

I really know nothing about brad sizes. If I don't buy any air nailer,
I will probably use 1 ½” brads to attach the backs (with glue of
course) but a pneumatic nailer would make the job a whole lot easier.
I think ¾” or 5/8” brads of any diameter would be good for the trim
but I question if 18 ga. x 1 ½” would be big enough. The piece will be
built-in, and screwed to the wall through the plywood back, which is
the reason for using the ½” plywood instead of ¼”.

Question #2: Some nailers also drive staples. What are staples good
for? Upholstery? Insulation?