Ok so you don't need to throw to second on the inside move but you can't feint and throw it over to 1st, so it would just come back to the umpire interpretation if he thinks the man on 1st gave an indication he would steal?
I'll have to ask some of my local guys and see what their opinion of it is, that really determines if we can do it during a game haha
Well, as practicality, you could because you're likely to have disengaged on the feint to second, so now, the balk rules aren't in effect. However, no, you couldn't stay contacted to the rubber and swing around to first with a feint to second during the trip (that would be rather awkward, anyway)
As to your second point, coming from a guy who used to use this a lot in youth ball, don't expect every umpire to know this rule. However, more will be aware of it than you would think. Do, however, expect the opposing coach to blow a gasket.
As to the "drive a runner back," in the FED rules, most umpires are actually going to interpret it more like the OBR rule.
I have a lot of experience with this and it is extremely useful at lower age groups where runners steal on every pitch. However, as you get older, "guessing" correctly as to when a runner is going becomes more risk adverse. After about 12u I only used it in two situations:
1) I've stolen the signs and I know for a fact he's stealing; and
2) the guy on first is a base stealing stud, quite likely to go at any time, and my battery has no chance in hell of throwing him out, anyway.
The oft offered objection against my interpretation is "well, why don't you see them use it in the majors, if it's legal?" It was tried once, that I know of, a couple of years ago with Hamilton on base, and he wasn't going. By the time you reach that level, there's almost no runner/catcher combo where you don't have at least a chance at a CS, and almost no runner where the chances of guessing he's going is any better than one in four or so, so the risk isn't worth the reward.