formation doesn't change, they will just put him where it makes the most sense. So your RB would play either CB, CDM, or even wide midfielder depending on his stats.
I cant speak for NG version, but if work rate is the same as old gen, then it doesn't mean anything as far as playing the game is concerned. Nobody really knows how work rate effects the game, but I have a feeling it might effect sims. You can change the work rates of each position, that seems to have a bigger effect then individual work rates.