can an imperial figure use the same surge ability more that once on the same turn? If the figures card list ~: +1damage and I roll 2 ~ can I spend them both to do a total of 2 damage?

A figure can only use a specific surge once per attack.

Yes, but only once per attack. Each ability can only be used once per trigger opportunity, including surge abilities. (unless explicitly specified otherwise)

(There are figures with Assault, and other ways to perform multiple attacks per activation.)

You can with this only http://cards.boardwars.eu/Ally-and-Villain-Packs/Wave-1/IG88/Agenda Deck/Firepower+Upgrade.jpg and only droids for that mission.