Just remember the temp strip on the outside of the carboy / bucket whatever is always a few degrees cooler then the inside. As far as Hefeweizens are concerned Polamalu is right, if you want a more banana fruity character ferment a little higher. I am not sure exactly which yeast strain you used, but the WLP300 yeast likes the 68' - 72'F "internal" temp range.
Using an air pump with no top should be ok, you could just put a home made sanatized foil cap around it to stop anything large from falling in. But the air pressure coming back out will keep most anything else small from floating down inside.
In any event it sounds like everything was done right, so you shouldn't worry!