if i will buy just cause 2 from amazon its will be to steam?

yes

Too goddamn lazy to look it up in the catalog. Link to it and I'll check for you.

Go on the store page, CTRL-F and search for steam.

it uses Steamworks as DRM so it cannot be played without steam so... yes

http://www.amazon.com/s/ref=nb_sb_noss_2?url=search-alias%3Daps&field-keywords=Just+cause+2 can you tell me what of thos i need?

Yes, all Just Cause 2 should be redeemable on steam, it's steamworks.