Quick question - I’m considering getting the AS Visa with a 40,000 point intro bonus. Can I buy a coach seat with miles and then when the miles hit my account from the Vietnam trip, can I upgrade to First without paying an extra fee?

What is is the likelihood of finding a coach ticket now on CX using AS miles for flexible dates in early November? Would be flying from MNL-NYC. I right now would have about 56,000 but by time the return flight credits I would have 72,000 approx. which would be enough for First coming home. I’ve read that CX opens First up sometimes within a few days of departure. Would it be reasonable to expect a minimum of business ticket back? Where can I search for CX availability using AS miles?

Sorry for all the questions. Thanks in advance.