I'll take a stab:

1) No, once you get down to T-24 the price you paid for your ticket doesn't matter. It's basically an upgrade free-for-all. Theoretically the upgrade list stays intact, with Golds before MVPs before the unwashed masses. In practice it's questioned whether that's the case.
2) Check in early and often! At some point those seats should get released, and you want to be there to snag the ug when they do! Unfortunately U availability is masked from now until the flight, so tools like EF won't help. The best advice I can give is to keep doing OLCI as often as you can. As soon as you get to the page that says request earlier flight/request later flight, look for the request complimentary upgrade link. If it's there, click it and you're set. Otherwise, just abandon the OLCI, it's of no further use.
3) Airport takes control at T-24, but OLCI obviously has an interface to the data, so you can still use it to snag upgrades.