hits are *all* hits, that is body+head, so hits+headshots = bodyshots + 2*headshots
and since (without adrenaline) a headshot makes 40-50 hp and a bodyshot 18, hits+headshot is roughly proportional to damage given (at least with mp40/thompson)
Accuracy? Players with a high accuracy are those who don't preshoot and don't gib, check for example some ettv matches where they have maybe 40 acc, while in public etpro servers the same players get 50 without even trying hard.
I can get 50 acc if I play for accuracy, but since I'm not a good player I won't get 50 if I play normally like those skilled players, so it's not a reliable factor imho.
As regards the fact that headshots = skill, I don't agree. Imho damage = skill. Some players give many hs but have a poor accuracy, so they give less damage in the end.
You don't aim for the body or the head, you aim for the area that gives you the highest chance of giving damage, taken into account player distance and animation, weapon spread, etc.
Let's say you have rifle and your opponent is crouching and he's far, where do you aim? Head? I would aim at the bodybox