School me on E70s

So with the new X5 due in 2014, the prices of the E70 seem to be falling nicely

So I know I want the 3.0D but there are so many variations of this.
Activity, Dynamic, Innovation, Sport, Steptronic
Then theres the sd and the xdrive?

Also a friend said I should try to get the single turbo version instead of the twin turbos. so which model has the TT

So my question is whats the difference between the models above, which one should I stay away from and which one should I be looking for.

Thanks in advance