1.BA did not have The Black Rage pre heresy right because Sang is not dead yet
Right.
2.Were a all assault pack army fluffy for pre heresy?
Some Legions used them more than others. It was still a relatively new technology, so while I would say 'no'- that would apply to the Legion as a whole, not a specific army. You could definitely get away with saying that it was a strike force, though.
3.Would the Baal Pred be around?
See:
http://z15.invisionfree.com/The_Great_Crus...p?showtopic=883But yeah, it is.
4.Were all armour marks in use?
For Pre-Heresy, It would be safe to use Mk. I-IV. Mk. V was deployed during the Heresy, and VI was still in development until later in the Heresy. VII/VIII... no.
Looking forward to seeing your pictures. Red is a better color than Purple... but I'm biased.