Q:
Warrior Adrenaline bonus + Burst Attack
A:
I’m not sure on the first part, but I would believe that the bonus is attributed to the burst attack as you have the bonus when you trigger the attack. As for the second, the bonuses occur once you have a full bar, not just once you start filling up that bar.
I tested this. The bonus does apply to the burst skill that empties your adrenaline. Added note to wiki.