Grot 6 wrote:- I got a core Dark Heresy and Sisters of Battle books from The Black Library when the game first came out.
Do the FF books coinside with them, or do I have a standard issue POS product that I wil have to go back and rebuy the FF books?
No, it is pretty much the same book.
Grot 6 wrote:Nothing would be cooler then going back old school and having your character accumulate an army a unit at a time, and then later, as the RPG campaign continued, you would have your character running his own unit on the battlefield.
I'm not sure how well that would work out, being that the characters are Inquisitorial henchmen and not Inquisitors themselves and the system reflects that. Psykers are dangerous enough to their own party when one person plays them. With some house rules it could be done but it would be very time consuming and unwieldy as it is.
After getting used to the rules you might want to check out the Wiki page with extra info and homebrew rules for Orks and Tau and such
here.