I woudn't trust the batteries after a week, personally, I would cycle them - or at least put a good slow charge on them before flying.

As far as the engine/prop issue.... try an APC 10x6 or 10x7 prop before anything else. Not sure what came with it, but I've noticed that there's some difference in performance between props (ie: master airscrew vs. APC). Within certain limits - more pitch&same diameter=more speed, more diameter&same pitch=more thrust. Play around with different props to see what you like. They're cheap enough to experiment with. [8D]