I'm sorry, but in my opinion MIDI backing tracks is a dead technology. Professional audio backing tracks have way better quality than you can get with a midi track. I don't plan on adding a full blown midi player to the app.
Regarding the time coding: I guess you could already do that. Just press the timecode button during playback and the current timestamp will be inserted in the editor. Now just prepend it with midi@ and complete it with the midi command.