Anything from a 10x7 up to the props listed above should be fine. You'll get different flight performace of course, but you won't blow anything up or anything like that. For training, I'd say an 11x4 or 11x5 would be safe bets.

Going from 0% to 10% you will usually see a noticeable change in most engines. The engine will produce a bit more rpm (which you might or might not notice in the air, but should be noticeable at takeoff), and should idle better (though with that flywheel on some of the Evo engines, you might not notice that either).