Hi fbelanger! Answers are below:
Can we choose to not support with a unit?
That's a good question! No, though I'm not sure why you wouldn't want to.
Quick Strike: The hero win the battle since is the only one to have dealt damage?
An unit can reattack if the battle was cancelled by Quick Strike?
A unit could not re-attack on the same turn if the battle was cancelled. They had their attack move already.
Are they interupt? Can we shield an unit before it take wounds? Or Heal before fatal damage?
Units can be shielded before combat, though they may be able to take out of damage combat before you get you turn to apply a shield. The enemy may be able to destroy a unit as well before you get to shield. Take care!!
Wild swing: The damage is done at the end of battle like acid claws?
The attacker's damage is calculated at the end of your phase of combat. After you deal damage, the enemy gets a chance to retaliate and deal damage to you.
Mining: When do you receive mana?
You receive mana at the end of your turn.
I hope these answers helps some. Let us know if you have any other questions!