put the stock reg back on. you've already bought it so whether it was a a good deal or not is irrelevant. they're as reliable as anything else that is taken care of. there is less lubing involved and a lot less frequently than with say, a DM.
usually around a case to every time i lube my engine. even that may be excessive. keep the bolt oiled with tri-flo though.
1) Milling & weight.
3) You do not need to lube it often. Maybe a once over after about 10 cases if that. Just the bolt (Triflow) & the engine (Dow 55).
4) That's an okay deal, but you should've asked this before you bought it.