Lets suppose that a unit open fire on a certain core team member (and just on him). The targeted unit cannot fire back, because the enemy is out of the weapon range. The rest of the core team shoot in ARO with all relevant bonuses. The attacker can fire on the designated victim without FtF roll, isn`t it? The same should be for the core team AROs from units, which have not been targeted. The firefight is performed without face to face rolls for this phase (order). Could you please confirm this? Or is the situation different ??
Assuming no Impact Templates: yes, it's normal rolls all around. If there's an Impact Template: Normal vs the main target, FTF vs all the other Troopers affected by the Template. The rule for FTFs is both Troopers need to be affecting the other.
The attacker's roll will be a Normal roll only if target's ARO doesn't include a roll that might affect the outcome of the attack. So, if you Dodge, it will be a FtF roll, but if you throw a Nimbus grenade (which doesn't have the Special Dodge trait and thus doesn't affect the outcome of the attack), then it's just two Normal rolls.