Yo, I just went from a Nissan to an e30 too, it takes some getting used to but there pretty decent
Oh, and I've been getting a lot of parts from bavauto.com, they have everything
( I still need an LSD though :( )
White smoke at idle could mean your dumping too much fuel...
Maybe you messed up an o-ring when you were putting in your injectors and one of them is leaking
Did you lube the o-rings before putting the injectors in?