You will usually see these bands participating in parades, public ceremonies, and the like. There are approximately 60-70 regular bands on active duty. Guard and Reserve bands have a similar number. The education level, while not matching that of the special bands, is MUCH higher than that in the regular enlisted ranks. There is no primary role for these bands.
Some bands specialize in certain areas, but most bands excel in all mission types.
I have, on several occasions, played a marching band ceremony in the morning, a public sit-down performance in the afternoon, and a jazz combo reception gig at night. Tell him or her that you are interested in entering that branch of service. Tell the recruiter that you are interested in being a military musician. At this, they will often be surprised as most recruiters are not familiar with the process. If they are familiar, you have probably stumbled across a bandsman that has been forced into recruiting.