So if i have Chopper (Rebel) on board as a crew if i pass through a Gas Cloud and Asteroid i Skip the perform action step.

Am i allowed to do an action and take a damage with Chopper?

Quick answer: No, you can't use Chopper that way (unless there are other mitigating circumstances).

Explanation: Chopper has a specific timing of "during the Perform Action step." If you move through or overlap either a gas cloud or asteroid, you skip the Perform Action step, so you never have an opportunity to use him. The only way you would be able to do so, would be if Chopper were loaded onto someone like Dash Rendar, who could ignore the obstacle (and subsequently, their effects) while moving.