Okay, you have Sabine, and you haven’t used your tractor token. You dropped two bombs in the system phase. After movement, an enemy (small base, or larger that has enough already that it can be moved) ship is in range of one, but just outside the second.

Can I detonate the first, apply the tractor token, do the barrel roll/boost to put it in range of the second bomb, then resolve that one?

Also, are we allowed to pre-measure bomb effect zones before choosing which to resolve?

1. I don't see why you WOULDN'T be able to do that. The controlling player chooses which bomb to detonate first, so you simply choose the closer one. When Sabine deals the tractor token, assuming the ship is small (or is otherwise 1 short of being "tractored"), you'd get to move that ship into the 2nd blast radius. The only thing I'm not sure about, is if moving the ship would (by necessity) go to the end of the ability queue, taking place after the game effects of detonating devices. I'm not sure you can slip it in between the 2 bombs going off.
2. As far as I understand, you're not supposed to pre-measure any distances, including bomb (or asteroid) detonation radii, until it's time to actually set the device off. To that end, you have to guess the explosion order of the bombs to maximize the potential damage.

this is interesting, there is very little mention of timing when it comes to detonating bombs. it happens at the end of activation and that's all there is to it.

it seems fair to assume bombs don't detonate all at once and the player who placed the bombs will choose in which order they detonate. if both players have bombs placed, the first player should detonate his or hers first.

there is nothing indicating you would be allowed to pre-measure.

other than that, you should be allowed to pick a bomb to detonate, use sabine (since she triggers after a bomb detonates, as in immediately after, before the next bomb detonates) to assign a tractor token, tractor the poor little bugger closer to you next bomb, then go on to detonate that bomb - and even go on to place a different token on that ship with sabine if you so desired.