I've got a question conserning questing.

If i play a quest card wich needs to accumulate 3 resources to use its action, what happens when i got enough resources?

Is the card then discarded? Or does it remain in play and just accumulates more resources?

What happens to the unit I played on it to quest?

quests stay in play. At this point, there is no way to remove them from the game once they have hit the board. When you reach the typical "3 or more" then you may use the effect on the card. You unit must remain on that quest to continue to hold onto those tokens and to accumulate more. As soon as the unit leaves the quest, the tokens are lost and you must start over.