Just a few quick questions...

Just hoping to get a few answers about some of this things in this game I haven't quite wrapped my head around. I have played plenty of RPG but this is my 1st Elder Scrolls game.

I get the leveling system for the most part, the more I use archery or a 1 handed weapon the more I raise levels in that tree. And every time I level up my character I get a perk/skill that I can assign to one of those trees. What I don't understand though is if I level up a skill let's say archery from 20-21 do I get better at archery? Do I do more damage etc or do I only get a boost if I add my perk to that tree?

Secondly I don't understand soul stones, how they work and really what they are used for. I have a bunch of petty soul stones that are empty apparently. So if I kill let's say a wolf does it's soul go into one of my empty stones? Or do I have to do something special to claim it's soul? After I get the soul then what?

Thanks in advance for the help. So far I am loving this game!