When do I have to spend the hit to have a card flipped?

Does the defender have to have damage cards already before he is attacked?

Examples:

1) The defender has spend his Defence Tokens and now there are 2 hits left, assuming the hull section has no shields left. Can I NOW spend one hit to deal one faceup damage card?

2) A Bomber attacks a hull section with full shields, the defender has a facedown card assigned already. I roll a hit. Can I now spend the hit to have this card flipped faceup without resolving anything else?

The hit icon is spent (so it doesn't count towards damage), before the defense tokens step.

So damage cards must already be there before you roll your attack dice.

Thus:

1) No - too late.

2) Yes - though you can still apply reroll effects or other modifiers before you choose to spend it.

It is during the modify step.