you are right - the one on the right in daniyals pics is the A/C idle up diaphragm. You would need this and also a 2 line vacuum solenoid (any type - toyota is best for it) - you would need to source this from a very good A/C shop or the junkyard - Tell them its the A/C idle up for khyber and get them to show you a khyber carburettor - then point it out to them.. Should cost somewhere like 1000 to 1500 to buy both pieces.
As for rpms increasing on A/C - whoever installed the A/C cut into the alternator load solenoid wiring and hooked the A/C to it. - just trace A/C wiring and cut the joint that goes to the alt load idle up solenoid. OR maybe be the A/C wala just disconnected it and used a new connection to the solenoid - usual easy thing they do. find the connector lying in the engine bay and test for operation by turning on headlamps connect to the solenoid and you would be fine.
The correct way of wiring the A/C is..
feed from A/C switch to thermostat in evaporator to condenser fan relay - take off 12v positive from condenser relay output going to condenser fan and trigger A/C clutch relay with this and also branch it to the A/C idle up.
That way if your condenser fan relay fails on you - your compressor wont turn on - saving your system from excessive high side pressure.
If you want to be more finicky - you can run your radiator fan along with the A/C condenser fan - but you would need to put a diode in between the positive wire coming from the condenser relay to the radiator fan - that way your A/C compressor and condenser fan will not switch on when the radiator fan kicks on from the coolant thermoswitch
As for tappets, adjust them once every 20K and do a good job not dheela sasta kaam.