Ref Visas. If you're not based in HK, you don't need a visa. And you don't need one to do the course. CX will apply for a HK CAD crew card which will allow you to travel in and out of HK while working for them. But it's only HK based personnel who will get a HK visa and ID card. Assuming your wife is a US citizen, she can enter HK on a 90 day tourist visa as many times as she likes. But she won't get a dependant's visa without you getting one, and she won't be allowed to work. WRTo studying, is it's a course in HK she's thinking of, some courses need an HK ID to enrol.