There's a useful thread building on the challenges and which mission you'll want to replay to get them: click here
. It seems that your faction will outright prevent you from being offered certain missions the first time through, but you won't have to do a full second playthrough.
I'm curious: anyone find it hard to get an "Insane" combo?
I'm only just past the Sublime boss fight, so don't know how much easier it will be to keep up a combo; I've seen "Great" and "Awesome", but haven't been aiming for them specifically. I've probably got the wrong power set for it: Density Control is mostly close quarter brawling, and if getting hit ends a combo, I get hit a lot.