If you want to use miles then Thai is probably your best bet. There are currently no direct flights to Hong Kong. Eva AIrways has announced that it will start services to TPE but I am not sure whether they have started yet.
For the porters at the airport just say no if you do not want to use them. I never have a problem with them. If you do use one then USD1 or 1000MMK is plenty as a tip.
SGD are not widley accepted really the USD is king so you should bring plenty of new unmarked unfolded USD notes. But the official money changers will accept SGD and Euro as well as USD