According to a news item I saw at Casters Realm recently, charimsa affects lull.
I personally cannot say how useful charisma really is, I have no real data to go on, but it SEEMS to make a difference in charm duration. When I have high charisma my charm seems to last longer than w/o it.
As far as it affecting mezz, I have not seen it change the duration of mezz. I do not personally know nor have any data as to whether charisma helps a mezz to stick, but I can say that Tash certainly seems to play a big role.
All this is just based on my personal observation. I have done no "scientific" test.
Good luck all.