1) The agent is right. Hawaiian Airlines is an AA partner for the purposes of the All-Airlines award, but it is not a member of the oneWorld alliance. Therefore it can't be used as part of an oneWorld-award ticket.

2) You can't upgrade a mileage-award ticket with another mileage-upgrade award. You have to choose to fly all the way in coach or spend the miles for a FC award. If you do choose a FC award, it covers all segments in the itinierary.

3) Yes, you can upgrade itinieraries to Hawaii using e-upgrades, assuming it's AA marketed and operated.

6) AA has no lounge in any of the airports in Hawaii, so it's a moot point. Back in the mainland, even a FC award won't get you into lounges, so that's also a moot point.