What was I wondering about
: How often were the aircrafts used to attack artillery positions?
As for "danger close", I believe those missions were fairly regular during pre-planned massive ops (like Market-Garden, though there they were mostly in potentia due to defects in communications etc) but then the planes were to attack specified targets (IIRC colored smoke shells were the norm). And most of the "spectacular" friendly fire incidents (air-to-ground) happened during highly mobile battles where frontlines were unclear (Guderian was almost killed in a Stuka attack in France 1940, Mac Arthur's car was almost attacked by a Lightning on Luzon in 1945).
The situation you describe (with kill zone >10km from own lines) would be most likely applied to more "static" periods, right?
Just for the record I think that the situation you describe above would be funny as hell and that adding similar randomness to the game would be great, but probably not worth the efforts and inevitable complaints, even if possible (having to tackle C spaghetti here and there, though not on a daily basis, my appreciation for it grows
)
As for the effect on tanks, IIRC there was an "online interview" with DAK Tiger veteran major (living in the US, discovered by a model/books store owner which he visited) who described the drill during air raid. Cars: leave road, crew+passengers jump out to cover. Tanks: button up and continue driving.