I just did #1 for my in-laws to visit us this past May. I booked them ORD-LHR-SIN return flights on UA/SQ using my UA MP acct. Everything went smoothly--no issues with the fact that I paid with my miles and used my Amex to pay the taxes. Also, they did get my status applied to them and I think they even got E+ at check in on UA due to my silver status...they were very happy. :-)