Why would you want to us miles for hotels???? I had an extra 100,000 BA miles that i needed to use ASAP before they expired (thats a free o/w F tkts anywhere) I used the same 100K to get 2 nights at the Copacabana Palace in Rio. What a terrible value but I did not need a tkt at the time and was spending a week at that hotel anyway. I am still kicking myslf for not just getting a tkt anywehere instead

Your 2nd question. I find having my Dubai address on my MP account much better then having my NY address. They have more promotions of you live overseas