Sagey,
As far as I can remember they actively discourage concurrent fixed and rotary wing flying, particularly when you are in the initial rotary bit. This is because of the pretty big differences between the controls and their effects.
After you've finished training and gone front line I think it's game on, fill your boots as they say.
As far as the AIB goes- I'm pretty sure they haven't changed the format in the last 30yrs or so. You could try to get a work experience visit to Yeovilton/Culdrose and poke a midshipman or two in the chest in the bar and ask them all about AIB, Dartmouth and flying training.
Good luck and be careful what you agree to, on my course at Dartmouth there was a guy who until he got there thought he was going to be a Pilot- they told him on arrival that he was an Obs- he wasn't very happy!
