Ruger LC9, iron sights, Crossbreed IWB holster. I have some 9-round mags and 7-round mags.
Given that you don't have any mags that even hold more than 10 rounds, you might as well shoot Production division. You can certainly shoot from an IWB if you like (though if you have a decent OWB holster I would suggest using it)---and remember you do NOT have to shoot from concealment in USPSA. (Matter of fact, we encourage you NOT to do so.
There are enough other things to worry about without making it even harder.)
You are going to want to use as many of your 9-round mags as you can...the 7-round ones will make your life a bit more difficult.
In Production, the big thing to remember is that (in addition to mag limits of 10 rounds) all the equipment and gear (holsters, mag pouches, etc) must be behind your hip bones---and you are going to need to carry probably five mags. If you don't have that many mag pouches, for your first match use all you have and drop a couple of extras into your back pocket. (Not your front pocket.)
....you know, I have a basic competition rig for a G19 (gun, holster, mag pouches, and mags) if you want to borrow it for a match. If you use factory ammo, you are welcome to try it that way. I remember you from IDPA, so I know you won't run off with my gear.
I also have a friend with a Colt Delta Elite 10mm single-action iron sights (basically a 1911), who might be joining. He's never shot USPSA either.
If it is a single-action, AND the holster is legal for the division, Single Stack is where he'd be shooting.
As Sean said, use the rules link and go to Appendix D starting on page 82 to see what division your gun/gear will fit into.
In general, you are going to want to (bare minimum) be able to carry 40 rounds on your body for any particular stage. Note: That may not be enough, but it'll get you through most. I'll note that I normally carry 60, and have been known to carry 70 (7 mags) on a long involved stage where extra reloads would save me time.
I'm crazy, though, so bear that in mind, too.
