What exactly does the cosplay team do?

See if you like COS or look at other people's COS

There are usually many departments in the team, such as COS department, makeup department, editorial department, logistics department and so on. The system of each club is different, so the departments will be different. They will assign you to a department that suits you according to your personality, situation and preference for COS. (It's like the COS department is specialized in COS; The makeup department is responsible for COSER's makeup; The editorial department is planning to arrange performances; The logistics department is a bit like manual labor, specializing in helping COSER with things and so on; Other departments will also have the corresponding nature of work. )

There are basically no special restrictions on age. As long as you like COS, there is no age difference.