Ok, so I try to understand how to approach it. Please let me know if I understand that correctly:
1. Vigilance is used when you are ambushed by combat (you did not expect it, for example you are at party and suddenly plasma bolts start to fly and people bodies hit the floor around you).
2. Cool is used as general and more common roll for initiative for any kind of normal combat situation and in standard fight.
Now what about situation like that (taken from last session): Player A is Mercenary, currently hired as body guard. He follows his employee and scans around looking for trouble, threats, potential security breaches, he is ready for combat etc. They are on some sort of gala. Rest of players are some other classes and they want to blend it, get some info. Gala goes on and on, suddenly random people in crowd start to pull out some blasters and explosives and screaming "for the rebellion, death to Empire!" and fight breaks out.
Now I would ask Mercenary player A to roll Cool because he was expecting combat and was actively ready for it. Rest of the players roll for Vigilance because they are surprised and caught off-guard.
Later when players investigate the case and it leads them to some old apartments at ruined city on the planet. When they enter the room, they see armed people who also look at them - players roll for Cool cause it's standard fight and they came here following the lead of very dangerous people (so fight can happen).
Do I understand that correctly? So mostly in fights I should ask for Cool and when team is caught off-guard (ambushed, betrayed etc.) they roll for Vigilance, yes?
Also if I have combat character in party who fully expects fight everywhere (he is veteran merc and always armed) - he should for Cool mostly as he roleplays that he is ready for combat because he doesn't trust anyone till he gets credits.
Sorry for long post, I just want to make sure I understand it.