i use a CMC trigger with the adj. for pretravel as well as overtravel. it has 2 little wings at the trigger bow - trigger pad junction. you just bend the wings foward so they contact the frame which limits the trigger's foward movement. a little bend goes a long way.
Probably not without soldering extra metal on the trigger bow or some other creative method to add a thin spacer.
You need take up (pre-travel) for the sear to reset properly. I believe the minimum is .040 inch.
Experienced shooters automatically take up the "slack" unconciously so pre-travel is not an issue. Some folks, however, feel it necessary to tinker.