Nice, I may just have to grab that, Deon.
@Asehujiko, about the ammo situation:
I generally haven't had this problem, but I try not to waste ammo. Use the correct type for the situation at hand-- don't pump an armoured enemy full of regular or hollow-point bullets or you'll soon run out. If you've got decent training in melee, don't shy away from using that as your main offensive and use terrain to get up close to your target if you're still a bit squishy. If they're fast, cripple their legs first. If they're strong, cripple their arms or whatever they're using to hit you with, then dance around them dealing damage.
Loot every body you come across. Every single body. Even if you think it's useless-- even if they were swinging a sledgehammer at you, they might still be carrying ammo. Loot every crate, box, cupboard, chest and footlocker you find. Pick up anything with a value/weight ratio above 10 caps per 1 lb, and trade them to merchants for ammo.
Speaking of merchants, scour their list of wares thoroughly for ammo casings. They charge nothing for these and they're weightless, so you should
always take it when you see it. Use them at reloading benches to create more ammo (protip: break down ammo types you never use for a healthy supply of those rarer components you never come across, like powders and such).
I think Freeside is the Rivet City you're looking for. It's just outside New Vegas proper. It's the first and only town I've encountered so far with more than one local merchant and there's specialist shops there too. Still, I'm disappointed by the rest of the towns I've passed through on my way here. They're all so tiny and barely inhabited. Then again, I haven't strayed too far from the main quest path yet. I'm sure there's bigger places I haven't seen.
Hope that helps a bit.