I can't give an exact number, but less than 30 out of a game with tens of thousands of active accounts. It doesn't take many turds to spoil a punch bowl, though.
It's a good idea and we do something along those lines periodically, but #1 by itself is actually a 6+ hour query that has to be run when there aren't a lot of other server-intensive things going on. EDIT: Which we will do in emergency cases anyway, but it isn't something we can just do all the time.
The reason we keep playing whack-a-mole with the energy thing is because to well and truly kill it for all time no matter what people were doing, we would have to put some stuff in place that would make it so that thousands of innocent accounts would have serious trouble interfacing with the game. Which has actually happened once or twice in Modern War or Crime City and explains a couple of the "omg GREE why do you guys keep doing this" moments (the answer being "we deployed a security upgrade that snagged on something client-side").
The situation with people purchasing the out-of-store LTBs is a similar case, where we are working on a more difficult way to stop that from happening. I say "more difficult" because all of the easy ways would have potential unforseen side-effects like a couple thousands people waking up one morning to find all their legitimately purchased LTBs missing. That would not be good. A couple dozen people purchasing those when they shouldn't be able to is also unfair, and not good, but that would be measurably worse. With large-scale changes of any type, we have to weigh the potential collateral damage to the gameplay of our playerbase as a whole.
Anyway, the long and short of it is, sometimes there are no easy/simple fixes for something.