1) limp/call preflop from EP is often set mining, rarely AQ/KQ.
2) flushdraw less likely as mentioned before, b/c you have the flush ace, plus he'd probably check/raise with a flush draw for better fold equity
3) is it not a decent option to call his flop donk bet and re-eval turn? Mind that lots of turn cards will also improve your equity, even against a set (most clubs, king, jack, ace,...)