Always full length size, and as Phil mentioned some rifles will need to use a small base sizing die. I've reloaded for more semi auto 223's than I can remember and have never needed small base dies for reliable function but I may have also just been lucky, you won't know till you try though so just make sure the case drops fully into the chamber and it should fall back out when you tip it muzzle up (a small amount of resistance is ok but you shouldn't need to ram it out with a cleaning rod).
I also prefer to use the Lee factory crimp die with my semi auto loads as well, you don't have to crimp but it's a good practice in an auto loader.
As for the actual reloading, I prefer a powder slightly slower than what I would use for a bolt action for the same projectile weight, it will help keep carrier speed down a little which is easier on the action and also helps reliability. Start low and work up slowly watching for pressure as you go just like a bolt action. The semi will be a little harder on brass than your bolt action so keep a close eye on it and don't worry too much if you get dents in your spent brass, it's usually just the shell deflector and the dents mostly come out in the sizing die. Some rifles are worse than others for the dents but I don't remember reading that the XCR's are overly hard on brass.
If you have them around try Nosler 60gr Varmageddon projectiles over CFE223, they've worked well together for me in a few different rifles. AR's are pretty easy to load for though, they are typically overgassed and bleed off excess gas once the bolt travels back in the carrier so they're pretty forgiving.
Good luck