He doesn't need any UV. If you put the cage in sunlight, be careful not to let it overheat. Letting him out for fresh air is fine, just be sure you don't let him hop where any chemicals have been sprayed recently.

Has he been acting like this all winter? If so, there is probably nothing to worry about. These guys just sit tight through the winter months, even indoors.

I think you should offer him more food. My Hylas eat 6-10 crickets a week.