I've had no problems with HARM, just be sure you use it on proper target, ie. SAM site. The most useless missiles for me were the IR versions of the Maverick, in some missions the laser-guided ones were unavailable.
Didn't put too much of effort for the allied computer pilots ( just give them something and let go), I'd usually bomb up my F-16 to the teeth and unleash the havoc.
Other sim from that era I've enjoyed was the Silent Service II, ie. the submarine ww2 sim.