Not entirely sure on this, but i think the anti-air script is used when you have directed flak guns. For example, you set an 88mm and an acoustic locator. You link the locator to the gun (i think it's the "set target" command) and then add the AA script and give it a sufficient radius so that it includes these objects.
I'm not exactly familiar with it, i simply tried it on a sample FMB mission a few weeks ago where i had a few blenheims attacking an airbase, so i can't be completely sure. In fact, i think i even forgot to link the locator to my guns, so maybe it works on non-directed guns too. For what it's worth, it seemed to me as if the flak was much closer to the Blenheims than what i've seen when flying online, in fact the smaller caliber guns were bracketing the bomber formation pretty well with fully automatic fire.
As for the emergency car, maybe it's an ambulance?
Set up a suitable ground unit on the airfield, place the emergency car script on the center of the airfield and give it a sufficient radius. Then try landing/crash-landing in a damaged aircraft and see if he comes towards you. This reminds me of the old red baron II, whenever i would land with a damaged aircraft a small ambulance came rushing to me. I haven't tried this, but it's worth a shot
