Where can i see my companions skills and stats, there must be a way? Or do they automatically have same skills that i? I know that for example lydia is warrior so she likes to use 1 handed, two handed, heavy arnor etc. But i would really like to know what skills they have, how much HP and magicka and all that.

Pretty sure it can only be done on PC, via console. If you're on PC, hit ~, then click on your follower. Type:

getav health
or
getav onehanded
getav sneak
getav marksman
getav stamina
etc.

Companions have unique stats that match their character - most housecarls are heave armor, sword and board tanks. Jenassa on the other hand is decent at sneak, but Aela is better, both light armor skilled. The level of their stats is determined when you first enter the cell they're in, so followers you come across later in the game will generally end up with better stats. They can be updated though via console by selecting the follower, then typing:
disable
enable