Suburban Man

If you do decide to go toroidal, this looks about right. Since it has dual primary - ie the mains side, you do need to get that right and wire for 230v (ie both primary windings in series) https://uk.farnell.com/block/rkd-120-2x30/xfmr-toroidal-120va-chassis/dp/4209599

Valid! My Baritone was longer scale

My limited experience of using a baritone is that chords mostly sound like mud. Bass or lead lines with a plectrum seemed to work well

The didgeridoo duel should be mandatory in Spinal Tap 2 🙀

And those controls are: Volume, tone and What exactly?

I’ve used K&M stands for years, well worth the money and you can almost always get spare parts for them.

This amp doesn’t have Speakon outputs so be careful with the amp-to-speaker cables. Like Dad3353 says, if you’re going to do any damage it’s likely to be this end of the system.

I used to build equipment for BBC Outside Broadcast vans and a standard piece of kit to have onboard was an earth spike (just a piece of nice solid copper or steel with a tag to attach an earth cable). You used it if you were (typically) powered from a generator or mains source a long way away and you just knocked it into the ground local to the van and connected it to the mains earth terminal of your electrical distribution - which could just be a simple set of sockets. Easy to do when you had an earth terminal specially provided for this purpose, but not impossible with a standard 13A board. It does need to be a solid piece of mains cable however; 2.5mm minimum, 4mm better. As noted by many others, wireless connections give an element of safety as do RCD's on the power outlets. The problem with a wireless connection is that you might want to adjust a control on your amp/combo and only then would you discover if you and the equipment were both connected to the same earth.

You just use left and right outputs as separate feeds - one for the PA (left), one for monitors (right). The Pan control on each channel acts to control how much of each signal goes to left and right - so a channel panned centre goes to both PA and Monitors, panned full left PA only, panned full right Monitors only...

When you say “monitor mix” do you want to create a separate mix for monitoring, different from the main mix? If so you can do that as long as you don’t mind your main mix being in mono.

Thinking that I may as well be hung for a sheep (ie a seriously expensive bass) as for a lamb (Rich's excellent EBS Session 60), I have just blown the year's budget on this very beautiful Duesenberg Motown Bass Almost too beautiful to play, but not quite...