I'm currently a plebe (soon to be recognized Mid!) in Band Co.
1.) Selection and Playing an Instrument: Band Co. selects people who put down somewhere in their application they were involved in band at some time in your high school career. So if you put "I played trumpet freshman year of high school" Welcome to Band Co. We do have a good number of plebes in Band Co. that have never touched an instrument a day in their lives. For those people, they play what's called the timpani drums and literally twirl sticks or they're part of the infamous symbol squad and clap their hands together. Everyone is assigned something even if you have no musical talent.
2.) Differences between Band and The Others: We are different. You'll hear a lot of different things depending on who you talk to. Some people in Band hate it so much they transferred to a different company within the first month. Others appreciate Band. I personally enjoy my time in Band Co. and wouldn't want to be in any other company. Again, not all of us (plebes and midshipmen) feel the same way. There are perks, however. We've won both Best Cleaning Stations and Best Rooms for the past two Command Inspections. Our dorms are always clean and cleaning is a major focus in the Band barracks. Whenever we've had special guests visit campus, administration picks Rogers Hall for them to tour as we have the nicest barracks to show off. So that's a big perk, I personally enjoy living in a nice clean environment. There are many other differences but the best way to know is to visit Band and get a feel for it.