Bugsy
1) I use the US version RC-8000, and when you get done with a Sys. call function you must then go back to the page or device that the volume controls operate on. The system call section does not have a "0" page, which has the vol., ch., and mute functions on it.
2) User menu allows access to the remote settings and can be turned on and off from the editing software to restrict access. If you don't have the setup manual, you should download it:
[Link: dufflers.nu]