It only re-rolls dice in pools.  The advantage of playing this card is that you can force your opponent to re-roll a great roll.  If you only want to re-roll your cards, you're better off discarding it for the game's built-in action.

I think not.  Per the RR, page 10, under "Dice On Cards", it states that such dice are not active and cannot be manipulated.  Secondarily, although there seems to be no glossary definition of the term "Reroll", the language under "Discard To Reroll Dice" on page 14 indicates that rerolls only apply to dice in the dice pool.  Hope that helps.  Thanks!

I'm pretty dubious about this card.

Compare to Scramble:

"Spot a yellow character" is a mild limitation.

all of an opponent's dice vs all dice, I'd say all dice is only SLIGHTLY better, and then only because you can partially time this to exclude your own dice if you have strong dice.

However, those limitations don't justify 1R difference in cost. I'd rather have seen this card cost 0R, and have some different mechanical drawbacks. As it is, resource cost is a big downer on an event this random.