Hang the feeders from wire or string with sticky stuff on the hanger. That solves the ant problem entirely. And I have never seen a hummingbird feather on the sticky hanger - they just don't go there.

I think shade is the best location for the feeders as the nectar stays fresher. I even suspect it is more enjoyable for the hummers.

I don't know that directly, of course. But I put out 4 filled feeders at the same time last week and the ones that were most emptied the next day were the 2 in the shade. The 2nd day, the ones in the shade were empty while the ones in the sun were almost half full.