Kind of ran across this thread late but it had some interesting ideas in it.
Fate point drought/monsoon: Still reading up on the system but my impression so far is that as long as a pure mortal character can still function beside your uber-whatsits and you can see that they have noticably more fate points to spend, then anything beyond that is a group or GM preference. Supernaturally powered characters have "always on" power, pure mortals have problems and complications interspersed with bouts of dramatic coolness fueled by sheer adrenaline and Fate points.
PC or NPC powers: I recall reading somewhere that they deliberately avoided labeling much of anything as an NPC power because people are comfortable with different things in their games.
Relative power levels within groups: Many games don't bother too much with power level balancing between characters. The basic character choices (templates or classes for example) are usually at least somewhat balanced but you can twink out in any modern game system if that's your goal. GMs generally have to keep an eye on that themselves. To some extent it's also not about how much you can use or abuse power either, it's how you play. I've had characters handed to me in other games that could have single handedly devoured the whole party I was in but at the same time I worked out motives with the GM that would keep it hidden in the background for a later dramatic reveal. This works fine for me because I'm more of a story-centric and subtle player. Some of the other people in the group really would have turned around and eaten the whole party though, so I'm hardly giving a blanket recommendation here. I guess the key question would be "Where is the fun for you in playing an untouchable uber faerie sniper that's a completed concept before play begins?" That's not a value judgement, the most important answer there is one you give yourself. Oh, one last problem with an imbalanced approach: No matter how much of a soft touch you are with the power, if you have it on your character sheet and other players find out about it (they usually will sooner or later) then you'll run into jealousy issues unless they trust you and the GM as much as the GM trusts you.
