Re: Neck sizing
Neck sizing only won't hurt anything. But if your die set did not include a body die, then you'll need one soon(they're cheap).
There are a lot of cartridges that can get by with NS & bump only, but most are not designed well enough. Shoulders still need bumping, and depending on a few things you may need some lower body sizing, or a lot of body sizing.
Either way, a custom die is often the best and most cost effective, as it combines the specific sizing needs.