When can I use Scatterbug's "Abnormal Outbreak" Ability?
It's pretty clear. If you are not taking the first turn of the game, then when you get your first turn (i.e. the second turn of the game) you may use Abnormal Outbreak. This is the only turn of the game when this Ability may be used.
Source:
Forbidden Light FAQ (2018-04-20), TPCi Rules Team (2018-05-03)
If my opponent receives a "Double Prize Loss" penalty where the prizes remain on the table and I play N, do I draw cards for the two penalty prizes or do I ignore those cards?
For N you draw cards based on how many prizes are still on the table, not based on how many prizes are needed to win.
Can I decline to take the benefit of a "Double Prize Loss" or a "Quad Prize Loss" penalty given to my opponent?
No, it simply changes the number of prizes needed to be taken to achieve a win condition. You and your opponent MUST sign any required Prize Card Penalty Slips, keep track of the new number of remaining prizes needed to win, and anything else necessary to implement the penalty.
In the case where both players have Pokemon Knocked Out simultaneously, which player takes their prizes first?
The player whose turn would be next takes their prizes first and then the other player takes their prizes. Then the player whose turn would be next promotes a new Active Pokemon if needed, followed by the other player if they need to promote a new Active Pokemon.
If one of my opponent's Pokemon is Knocked Out in the middle of a turn before the attack, can I take my prize(s) right away or do I have to wait until the end of the turn?
No matter when a Pokemon gets Knocked Out during a turn, the opponent takes their prize(s) as soon as all triggered effects have finished resolving. You do not wait until the end of the turn to resolve KO's and prizes.
The correct order for Milotic's "Energy Grace" Ability should be this: 1) Attach 3 basic Energy cards from your discard pile to 1 of your Pokemon (excluding Pokemon-EX), 2) Milotic is Knocked Out. That means you cannot use "Energy Grace" if you have no basic Energy in your discard pile, and you can't use "Energy Grace" to get back any Energy that are attached to Milotic.