Generally, I use whether the NPCs are under the refresh level to determine whether they get fate points: If it's a 10 refresh game, and High Lord Whatshisface is at -17 refresh, he's not going to get extra fate points for self/GM compels. But if his underling, General Whosthat, is sitting at -9 refresh and gets a compel, he'll get one.
But, if the players do the compel, I do hand over the fate point to the NPC to preserve the whole 'action-reaction' thing.
As for NPCs using fate points, mostly I just go the GM-fiat way of it to make life interesting for the PCs.
Most everything that happens in my games are from the players' points of view, anything happening offscreen I just work out in my head or something, usually while they're doing a GM-free character development bit.