Fighter Swarm

a reply from Richard Borg

(RB) First Strike and Ambush is only played against one attacking close combat unit.In the case of a Fighter Swarm, the First Strike and Ambush card is played against just one attacking close combat unit. In the case of a Fighter Swarm a Battle Back must be played against a unit that is attacking in close combat first if any. Other wise when both Fighter Swarm units are attacking at ranged the battle back is against a unit of the battle back player’s choice.

Let's say 3 fighters swarm one enemy unit. And the opponent plays First Strike/Ambush. Does he get to choose which of the 3 units he strikes first?
(RB) Yes 

If one of the 3 fighters is eliminated by the first strike, is the entire swarm attack called off, or do the remaining 2 units still combine their attack dice and attack without the unit that just died?
(RB) Yes - I'm presuming the latter option. 

Can the defender choose the target of the battle back?
(RB) Yes

Not really clear what happens when this attack is countered by First Strike or Ambush, nor in the event of battle back.

There is a BGG discussion here
boardgamegeek.com/thread/2188535/fighter-swarm-and-battle-back