Ranged Weapons - effect of range on THAC0 / damage? Also spotting?

Hi, I've been looking a bit more into the mechanics of ranged weapons recently, and am unsure about some aspects. In a previous thread (this one: http://forum.baldursgate.com/discussion/6468/str-damage-bonus-for-thrown-weapons#latest) I've asked about the effects of strength on thrown weapon damage.

I'm also unsure of the effect of range on THAC0 (and perhaps damage, for some?). Many ranged weapons have a range greater than sight, so I was wondering if there is a bonus THAC0 for some ranged weapons when used quite close to an enemy - e.g does firing a composite or longbow at, say, range 10, give you a better THAC0 than firing at maximum sight range (it should, I shoot a bow IRL and its a damn sight easier to hit something at 20m than 60m...) or once you reach sight range or maximum range (whichever is less) of a ranged weapon, does THAC0 remain constant? Does damage also remain constant?

Lastly, most bows have a range or 100, which is more than sight range, is it possible to fire them at this range with a "spotter" (e.g. a hidden familiar)? I've not got this to work, but perhaps its possible?

Just trying to think of some ways to maximise effectives of ranged weapons...