Right Derek,
Managed to see what you are on about.
I can see why he has used stainless for his pipework, just look at the redline on the gauge - 12 bar (approx 175psi). Maybe he doesn't like picking pieces of copper or brass out of his face.
With regards to the big v-twin, that looks like a poppet valve, high speed, single acting unit.
Belt drive from the crankshaft is standard for this type of governor.
Without seeing all of the boiler it might be a bit difficult to determine the use of the other bits, they might be for controlling the water and fuel flow plus ignition to what looks like a flash boiler, especially as it looks to be made of stainless, which I think was the standard type of boiler for a high speed poppet engine.
John