I have never seen a "bald" flight attendent who was male on a US originating flight but since every airline has different rules in regards to what they allow you should check directly with the airline you are interested in.
Yes, cleanly shaven men common in the industry. It really depends on the airline and the nation that the airline is based in. For example, in India, if a flight attendant is male and Sikh (Religious belief) then he is allowed to wear his turban and have an unshaven face. Here in the U.S. the airlines determin what is appropriate. For a very long time, it was inappropriate for men to be unshaven, and only in the early 2000s that many airlines changed the rule. I know that the rule is still alive and well with other carriers out there in the world.
Apart from that, most airlines do not allow long hair on men. The most that I have seen is that I have seen very small mohawks done, but not often at all. Usually the guys are very well groomed. Your short hair may be a blessing to you in that it is easy to maintain, something that is very important to airlines.