Okay. 1. So if I get a AR in .223 it doesn't necessarily use the same ammo as bolt-action .223.
2. If I want distance and precision go with a higher caliber.
3. Go with something like a Ruger Mini-14 if I want cross-compatibility.
Last thing...what's the hype of a .223 Wylde?
Really new to modern firearms..could use some advice.
An AR-15 chambered in 5.56 NATO will allow you to shoot .223 through it all day. A lot of times though, you can find 5.56 ammo for cheaper and it will shoot through an AR (or any rifle for that matter) chambered in 5.56 NATO, but you can't shoot it through a gun chambered for only .223. All AR-15s aren't chambered for 5.56 though (should be on the barrel).
Technically, the extra space in a 5.56 chamber can cause inaccuracy or inconsistency when firing .223 out of it, but I've not ever experienced this (but again, I don't attempt to make groups at great distances with my ARs, that's what I have my bolt-guns for ).
I'm not sure what you mean by cross-compatibility, but I wouldn't get a Mini-14 over an AR - especially since gone are the days of picking up a Mini for $250. At current prices for a Mini, you're very close (if not already at) AR-15 prices and you've got tons more options in the AR world (barrels, sights, mounts, stocks, magazines, trigger-parts, etc.).