I'm afraid you can't do that. I will mark this on my possible future changes list, but it won't be implemented any time soon.
Welcome to the game.
Not sure if i understood your suggestion, but currently you can move musicians between bands using Backstage (that you can find in band manage page).
About the game update, yes, now it should get far more frequent updates than it was before last update. The last update was kind of big work, had to basically rewrite game from scratch.