As far as I understand it - the only roll the commander must roll is the “Officer’s roll” on page 470 to set the dispositions of the forces.
Although I believe the commander is may not always be the FON, or the PC’s main character - One character I have played is a Corporate Exec, with a Chief of Security as her 2iC; the exec doesn’t know the first thing about a firefight, and so when it has come up it was the Security Chief who led the security team in firefights, with the Exec giving occasional words of advice. On the other hand if you had an incompetant Anvil Lord with a skilled Lieutenat; when the Anvil go into battle it will be the Lord who will be making the rolls (even if the PC is the Lieutenant), the best the Lieutenant can do is ‘Help’ the Lord (or arrange for the Lord to be elsewhere when a battle is iminent).
Most of the rolls in the firefight come use either Tactics or Command, so if you are thinking of having a character lead many firefight you should take both these skills (even at their root values it will be better than beginer’s luck).
If you want to use some sample character’s download the demo scenario (Fire’s over Omac) from the wiki. Several of the characters there are suficiently skilled in Firefight skills to make an interesting fight. While you are at it I (and many others here) recommend playing through the scenario first before burning up your own world/characters.