Is there any upgrade to regain energy faster in board meetings? That's my biggest weakness as I get higher into the ranking game (~22 atm) - while I tend to have some low cost characters in there, it still can drain quickly at times and I've had two sessions that I didn't end at 100% because I couldn't attack enough.
Also... Persona on Xbox!? -- at least some of the music! =)
As far as I know the only thing that affects energy gain is whether all your employees are happy going into the meeting, so make sure to heal up after every business day AND after you lay off a bunch of people which I later found out greatly lowers all your employees morale. I believe beating an enemy only gives health back to the one who lands the killing blow.
Make sure your low cost characters still have decent attack. Your aiming for as high a Charisma(which is ATK)/cost ratio as possible.
For energy efficiency, I always waited as long as possible before addressing a person (except the very first attack which doesn't matter since you're at max energy). Whatever your most expensive attacker is, have another character of the same color, with as cheap an attack as possible. This is to break shields, which die in one hit if you use the right color, regardless of attack power. Also, if an enemy has a sliver of health left, you can gamble and use one of your cheaper members attack even if they're the wrong color.
Also save up for grovel level 2, and then milk the stun for meter gain. I didn't find grovel level 3 to be worth it.