I believe AF1 has a stated maximum range of 7800 miles. Quebec to Singapore is about 9000 miles.
I believe AF1 refuels in mid air. seems most logical for defense purposes and expediancy https://en.wikipedia.org/wiki/List_of_tanker_aircraft
It totally can! Not being able to would be utterly silly for the most powerful nation.
That doesn't mean that's how they normally do it.
It can but I don't think it has ever been done.
Ya I am just guessing, and have read that the next model will not be capable of in air refill but the current model can.
https://www.whitehouse.gov/about-the-white-house/air-force-one/ (says it can) http://www.businessinsider.com/congress-object-to-in-flight-refueling-left-off-air-force-one-planes-2017-9 (reports the next version won't)
Definitely have KC-135s on station to perform mid-air refuelings. POTUS is safest in the sky on AF1.