An automatic has less felt recoil. Plus revolver ammo costs more than 9mm auto, so you're looking at a higher cost to practice. And that whole six rounds idea.... better hope that you 1) don't miss, 2) have less than three assailants (as you can't count on a single round to stop someone, despite what you see in Hollyweird).
I also disagree with your point about .40. It's still a compromise round, it's still not nearly as effective as .45 - as some police have been demonstrating of late, hence the creation of the .45 GAP and the .357 SIG.
Firecat: In case you're wondering, this is one (well, more than one) of those "Ford v. Chevy" debates that nobody ever seems to have a conclusive answer to - at least not one that will stop the other party from arguing.
Anyway, you will need the following gear as a firearm owner, both to care for the firearm and to shoot it at the range, as well as to keep for defense:
Safety glasses
Hearing protection device (could be anti-noise safety earmuffs, could be earplugs)
Holster
Magazine "pouch" or holster for extra magazines (to carry them with you); if you get a revolver, you will need this for your speedloaders
Cleaning kit - yes, Glocks come with a cleaning brush. It sucks. Get a kit.
Cleaning and lubricating chemicals - I'm partial to CLP Break Free and Gun Scrubber, with Hoppes or RemOil lubricant.
Range bag (duffel or something to carry all this stuff in)