Help in middle of game and need an answer

Would depend on the effect.

If it's a one and done type effect then no, you can't issue commands during the deal damage step.

If it's a continuing effect, then it would be in effect until the point you discard it.

No. You can spend a Repair command dial or command token when you first activate a ship and reveal its command dial. So if you're taking damage, face up or face down, there's no way to remove that card until the next time you activate that ship.

It was the structural damage

Thanks this is our first game playing

Ya unfortunately repair happens when you activate the ship and does not continue through the round. Even if you have a repair token, you must spend it at the time of the dial to use it.

It was the structural damage

No, you can't use a command when the damage is being dealt, so you can't avoid the 2nd card. However unlike Direct Hit! in X-Wing, getting rid of that card won't get rid of the extra damage, since you actually deal a 2nd damage card then turn that one over.

Yes it can depending on the order of activation

if your opponent activates first and fires at you and damages you.

You activate your ship and it has an engineering command dial you can then repair the damage his ship did to your ship.

This situational and conditional but yes you could remove critical damage before it takes effect.

Yes and no, depending on the damage. Repairing a crit which affects shooting prior to shooting: of course. Repairing a crit denying you the dial or taking a damage prior to the dial - no way. Repairing a crit with an instantaneous effect prior to the effect - no way.

This situational and conditional but yes you could remove critical damage before it takes effect.

No, the crit takes effect as soon as you flip the card.

Page 4 RRG - Faceup damage cards have either an effect that must be resolved immediately when the card is dealt or a persistent effect that applies while the card is faceup.

Now it's possible the effect of that crit may not actually do anything at that time, such as Compartment Fire or Damaged Controls. But you can't actually remove face up card before it's resolved, you may be able to remove it before it actually has any impact but that's not the same thing.