[Eviltwin]

am no expert but here goes some opinions:
1) Believe I've been reading that most gas port sizes have been .125 or smaller
2) By having the adjustable gas block you can use less of the extra gas generated by
supersonic rounds to cycle the action thus keeping wear & tear down on the gun or
in the more open position try to allow as much of the gas generated by the sub round
back through the gas port to cycle the action
3) To an extent yes, also certain muzzle brakes (Krinkov) have been used on SBRs to aid
in cycling
4) Yes, see above - it will increase the dwell time
5) 1:8 is the preferred twist for the 190rg and up bullet range, not sure on how short
6) I have a chart printed out somewhere, I'll see if I can remember my photobucket info
7) The tighter the better, think somewhere around 1/20" larger than bullet - so .358"