1. Use aux buses to 'mix' separate outs for performers.
2. Yes, you can use a patchbay for a pre-amp, but it is generally a bad idea.
A) It introduces extra signal chain and B) should not be used with phantom power.
I could suggest a million amps, but I would definately recommend a closed back cabinet if you wanna get "heavy" sounds. Mesa's, Marshalls, Divided by 13, Krank, Orange and many others rely on the cab to get their 'sound'. You might drop a 25W greenback in that Fender and fabricate a closed...
Junior travels light. Dodge Caravan with two guitars, probably four suits. You backline two Fender mid-70's twins, which he turns up to 10. Controls volume at the guitar. He's in, he's out, and he takes "cool" with him.
I own the R16. It is 8x2 in usb mode. The control surface works quite well. The standalone recorder is quite good. The built-in FX are passible for most demo work.
As a USB interface, I would look elsewhere. While I have achieved 8 in to Sonar, I've had to dial up the latency to about 50ms...
Hey, I have Traynor amp from 1979 too! It's a great amp, but it's too loud for the bedroom, and I don't really understand all the Canadian words next to the knobs.