Old Coach,
No need to reduce your loads in the military 5.56mm brass, although you do if you use military 7.62 or 30-06. The 223/5.56mm LC brass has about the same capacity as W-W or most other commercial cases, and even more than some.
You'll need to F/L size for anything you run through an AR, always, without fail, every time. A Small Base die's not a bad idea, either. though most rifles will run on standard F/L dies. Think of the S/B dies as just a bit of added insurance. Two items you didn't mention that are virtual necessities are a chamber/case gage of some sort, and a means of removing the primer pocket crimp for the first firing. My personal recommendation there would be the Dillon 600 Super Swage. Best tool on the market for this, especially if you'll be processing a lot of these cases. As to the case gage, you need some means of verifying just how much you're bumping the shoulder back. With a gas gun, you want at least .002" or a max of about .005" to make sure everything runs properly. I like the Wilson chamber type gages, too, as they make for a very good means of verifying that the rounds should chamber freely in your rifle.
