...or when to Ackbar.
I find Ackbar to be a difficult decision to make, he is often a large resource sink that will be difficult to properly time. You have to have a unit present in order to participate in an edge battle, for an attacker this shouldn't be a problem since there could be no engagement otherwise. The three open resources on the other hand can be a challenge at times, going into that situation your opponent could be expecting a Rebel Assault or Admiral Ackbar and plan accordingly. Unfortunately playing Ackbar during an engagement is the only time to take advantage of his reaction text to help clear the board.
I think playing Ackbar as the defender is an easier play to make. If my opponent opponent is playing a more blitz style and commits several one health units I just need to decide if I want to assign a token defender to either make them waste cards in an edge battle I don't care about or use the edge battle to cycle my own hand. In this situation I do not care about winning the edbe battle because the first action I take after the edge battle resolves will be to play Ackbar and kill all the opponent's one health units in the engagement.
The other defensive scenario is when you want to win the edge battle. this is usually when your opponent has high health units like Vader, Devastator or even AT-ST that Ackbar will not be able to kill in a single shot. In these situations I might play Ackbar after assigning defenders if I need to have presence for the edge battle. I might try to hold him until after the edge battle if I feel confident about winning the edge and use the first action to play him and strike with him first. This will let you lock up a target or two and possibly let you strike unmolested for the rest of the engagement. You can even hold him until your opponent has used all of his strike to deny the unopposed bonus and avoid Ackbar taking any damage from your opponent's strikes, this is more to buy you a turn when you desperately need it.
As the attacker one thing is above everything else you have to have a unit to declare in order to engage an objective, I have seen some people try to declare an objective hoping to play Ackbar unopposed. Unfortunately you cannot do this tactic. Now if you declare an attacker and you opponent removes the attacker you will be able to play him since the engagement isn't canceled by removing the attackers. Now unless you play Ackbar after the other attacker was removed and before the edge battle begins you will not be able to put anything into your edge battle since you have to have presence to participate.
On the attacking the only almost auto-play I have is when they only assign one health defenders, you might have this happen once on accident after that I would expect they are trying to see if you have Ackbar or Rebel Assault and want to bait them out of your hand. In this situation I usually just drop out Ackbar and take the board clearing I can get. If you get three units Ackbar did far more than you should expect. Now if you feel they are baiting you, you can hold him for the next defensive turn and see what happens. After that it really depends on what I have seen of my opponents deck and what my hand looks like for the edge battle.
In closing this is all just opinion and conjecture of the 20 or so games with the deck. Board control with the Rebel Alliance is something that gives me hope for a type of Light Side control deck but only time will tell.