Had this come up last night and just wanted to be sure

Zuckuss can only be used once per instance of a ship defending correct? You cannot say make Soontir reroll hs two evade results at the cot of two stress and then if he gets a blank and evade on the reroll make him reroll the evade again for another stress since you can only ever reroll a dice once.

Correct, each die can only be rerolled once. Additionally, he only triggers once, so you can't reroll the evades then later choose to reroll the eyes for whatever reason.

Also, her prevents further rerolling by the defender. If you reroll an evade away, he cannot use Wired or Lone Wolf or what have you to reroll again. Each die can only reroll once, no matter the source.