The MSB and LSB are both based on where the folder with the song is located on the Beat Buddy. Nothing else. No, they are not already assigned, because Ultimate Guitar does not know where your songs are on the Beat Buddy. Yes, set up a folder and assign them as you go. But, you won’t use the footswitch to change songs; you’ll use OnSong. OnSong will tell the BB which song to pull up. It does not work vice versa. BB won’t tell OnSong which song to display. You’ll create the set list in OnSong once you have the MIDI numbers assigned to the songs in OnSong.