welcome!

1) i always just check kayak or something to look for flights. with minimal miles to use, i don't think there are any options with miles + $$. timing might not be best for cheap fares either, so good luck!
2) like wwtsang said, your eupgrades probably won't do you any good. they're pretty much useless without at least elite status. sorry! i was prestige for a year and was only able to upgrade once or twice during their summer promotion, when any status could use upgrades on a cheap fare.
3) if you don't plan on traveling much next year, there is no point in keeping status. your miles are valid for a few years, but your eupgrades expire in feb '12. i'd suggest just saving your miles for the future.
4) don't understand how going UA will help with status. no matter how you travel, you most likely won't make the necessary 25K miles to get silver status. you will need 50k for gold status, but still won't have lounge access at domestic (USA) lounges. check out the *A website to see what the qualifying guidelines for each *A carrier and chose what fits your needs!

good luck!