Hello and welcome nice looking saff, likewise about meets

The Amal valve (Solenoid) is missing you actually only have the casing. You would need another soon as you can't buy the two bits separately. That is actually very dangerous as you have no boost control at the moment.

There should be a black electrical plug which connects to amal valve which I can not see in picture so see lying round near the slam panel.

Idle issue I have the same issue with my car I just disconnected ISCV is a common issue, but ideally you would want to replace sometimes a clean with WD40 or the likes can sort.

Good advise for fuel pump wiring + filter also make sure your cooling fans work, they may have already been re wired which is more than likely.

As for lights check to see if number plate lights or back side lights can't remember which way round now work, if not will more than likely be the fuse as this protects these along with the panel light circuit.

As for wire behind cassette can't answer but make sure none of the wires behind here are trapped/exposed as this could be shorting causing light problem.

Martin