That's a cute tank.
I think I've read to keep the light on "only while you are enjoying your fish," and to keep it off the rest of the time, just letting the natural light and the light of your house light his tank. Otherwise, the bright light on top of him all the time may be stressful for him. But if you use it just when you want to watch him in the light, it should be just fine :).
I have a 3.5 gallon and I have a pretty good filter on it and my fish seems okay, so I don't think bubbles would bother your fish too much. Just make sure he has enough space to swim around without being knocked about by something :).