That's a lot of questions.
This is only my opinion but, things are scarce right now but try to pickup a reloading manual, Winchester or Fed small rifle primers, and for target shooting...any sierra match king bullets. Bullets are tough to find right now so you may need to settle on what you can easily find. I assume you have good brass. For powder, my first choice would be H322 but there are many useful powders to have for the .223. A lot of people have great luck with H335 also.