anon125, ALSO, you can use a foot switch to change registrations sequence based on a sequence you program so the registrations change without having to push the individual switches. (You can also assign one of the assignable buttons under the screen to go through the registration sequence, but then you have to push that button each time you want to go to next programmed registration in the seq.)....the idea is to setup all the regs you want for a complex song, then step through as you play all the sections of the song, very nice. Frees your hands up if you use the foot switch.
As to the switches for turning on/off each kbd part L, R1, R2, R3....those will typically be setup by a registration, AND one or more will be set to on, you can while playing turn on or off each as you want...as example you might start with L and R1 and R2....then in the next part of song reach up push R3 to add, let's say a solo Violin. OR all that can be done with registrations as they are the king of using the keyboard efficiently.
Lee