I’ve been thinking about implementing selection of multiple tracks, but it will take a bit of work to do this, so it will have to wait a while.
To organize tracks into groups, you use the ‘Increase/decrease group level’ menus in the track context popup menu, or use the Ctrl+’Plus’ or Ctrl+’Minus’ keyboard shortcuts. If you want to shift the group level of an entire track sub tree, you just collapse the group before using the increase/decrease commands on the top track in the group.