1.) The only schemes that I'm aware of that can do BA upgrades are BA's own program and AsiaMiles. The QF experts would know for sure, but I don't think they offer any BA upgrades.

2.) Well, a HKG address would force you into Asia miles. UK, US or Canada are on equal footing. The only major difference is that you are only eligible for regional promotions that match where you are registered. (For example, right now there is a triple miles in Club World or Club Europe offer for the UK, for Europe members the offer is triple miles in Club Europe only, and there is no offer like this at present for US/Canada. You also have the issues of BA mileage credit cards which differ for US, Canada and UK members.)

As you allude to, it still takes less tier points to qualify for gold and silver for EU members.

3. Correct.

4. Based upon other threads that I have read, I believe the answer is "no". (Note: We're not talking about upgrades here, where you do earn miles for the class from which you are upgrading.)

5.) No. The ticket has to be purchased from BA directly.

6.) It's very subjective. I gave up WT soon after WT+ was introduced. And I've since given up WT+ for NCW. The best deal is if you can buy WT+ and upgrade to Club with miles. (Or in your case, take a cheap flight down to LIS, and book one of the cheap EX-LIS First fares to HKG.)