Need some help with my RG-50TC

Just bought an RG-50TC tube amp about a week ago. I jammed with some friends on friday (last week) and when I cranked up the volume, when the volume from my guitar was a 0, I kept hearing a weird whistling in the amp. Kind of like a bird dieing inside the amp (I don't know how else to explain this). It doesn't do it at lower volumes thought.

Also, is it normal that :
I hear a buzz / hum when I don't play anything (I know this usually happens with Solid State amps, not sure about tube)

When I switch from the clean channel to the dirty channel, I hear a large *POP* coming from inside the amp.


Also, the shop ordered me a footswitch because they didn't have one in stock, and I'm not sure they'll come through with this... is there any way I can order another one from somewhere?

The 'large pop' when change the channel happens with footswitch too in my rg50tc, but if I change from clean to Od when it is in standby mode and then switch it on, every change you do sounds like a very little 'click'. If you switch to stby mode again, the next time you have to do de same i tell or will sound the large 'pop' at the first switch. The other sound try a Noise supressor or similar.

Buz/hum is normal in all type of amps. Especially with single coil pickups.