Some final code requests (and screenshots)

Does anyone know how to have the Empire music play until Leo is recruited, then play the old colosseum music?

If the map song is the Empire music, you need to set a free event bit in the Leo recruit event. Then at the end of the entrance event of the Colosseum map (which you can find in FF6LE), before the return ($FE), check if that Leo bit is clear, if so branch to the return (or $CA5EB3 would do), otherwise play the old Colosseum music.

Using free event bit 002, in Leo recruit event:

Code:

D0 02

Then before the entrance event return ($FE):

Code:

C0 02 00 B3 5E 00
F0 XX                       // change XX to your song ID

Edit: You won't have place to add directly this code, you'll need to use the B2 command in both places to call the custom code in another place in the ROM.

Edit: I just saw Gi Nattak's answer and it is a better way to do this.