Never ever played any of the baldur's gate games, where should i start?

I see there's baldur's gate, baldur's gate enhanced edition, baldur's gate 2 and some expansions.

should i just start with baldur's gate enhanced edition and then go to baldur's gate 2 enhanced edition? or?

Also, how is the co-op capability of the different games?
I have 2 or 3 friends i would like to play with.