First, the 1.8 uses the L-jetronic FI system, which is different from the D-jetronic system covered on Brad Anders' site.
The AAR is the Auxiliary Air Regulator. The FP is probably the Fuel Pump. I don't know what "H" would be. The 1.8 does indeed have an AAR and an FP.
Note that the 1.8's fuel pump does not do the ~1.5 second "prime" that the D-jet one does. Instead, it runs either when the starter is cranking, or when the flap in the air flow meter is moved. You can turn the key to "on" and reach into the AFM (Air Flow Meter) and push the flap with a screwdriver to hear the pump run, if the system is working.
The 1.8 uses a "double relay" that hangs off the relay board to power the FI and the fuel pump.
Check over at
http://www.type2.com , as the later Buses used an L-jet system very similar to the 1.8s and their FI tech articles should also apply to you.
--DD