the gun for cable is the t-25 from arrow which shoots round crown staples. it takes 3/8(for phone/data), 7/16, and 9/16(for rg6 coax and 16 ga spkr cable)
i run my low volt wire at least a foot from ac wire where possible, and always through my own drill holes. if you drill through the center of the stud, no drywall screw should ever reach it. if you are close to the edge, there are protective plates to nail up.
unless you're running the surround runs, always try to run through a volume control location. always pull home runs. use at least 16 ga. wire for speakers.
for me, i'd rather run 12 ga. wire than go through the braiding routine of the cat. 5.
jr