can drea's ability be used more than once per turn and what is the timing?
think about it.
drea takes a lock as an action
spends the lock to fire a torpedo, but takes a stress to re-acquire.
since the spending of the lock initiated the attack, can the lock be immediately used to re-roll the missed attack dice?
receives another stress to re-acquire a target lock on the defender.
using r4b11, immediately spends the lock to force a re-roll of dice.
receives another stress to re-acquire the lock.

can drea's ability be used more than once per turn ...

She can us it more than once per round.

... and what is the timing?

Good question, actually.

If she spends a TL to reroll dice, does she acquire a TL before or after that reroll?

drea takes a lock as an action

spends the lock to fire a torpedo, but takes a stress to re-acquire.

since the spending of the lock initiated the attack, can the lock be immediately used to re-roll the missed attack dice?

receives another stress to re-acquire a target lock on the defender.

using r4b11, immediately spends the lock to force a re-roll of dice.

receives another stress to re-acquire the lock.

That works just fine. With only two green maneuvers multiple stress tokens might not be a very good idea.

worse even still-
btl-a4
attack with primary, spend lock, re-acquire using ability.
using r4 b11, spend lock to force re-roll, re-acquire using ability
using btla4, spend lock, fire torp, re-acquire using ability.
spend lock to re-roll missed dice, re-acquire using ability
using r4 b11, spend lock, to force re-roll, re-acquire using ability
5 stress, 1 attack, 1 secondary attack, life is good

BTL-A4 does not allow you to fire a torpedo.

oh well... only 4 stress per turn

Just remember that if another pilot destroys the ship that has your TL on it, you will likely have so many stress tokens to ever gain a TL again. If you predict that will occur, when attacking of course, use R4-B11 (even if you choose zero of the defenders dice), then use Drea to move the TL onto another ship.

Oh, and never put the "other" TL on a ship with a higher pilot skill and the Pilot Talent: Expert Handling or Drea will cry.

Read this http://teamcovenant.com/immaterium/2015/03/12/a-closer-look-at-drea-renthal/

Great article.