I only use focus when I want to fire on the focused target. But yes, if I focus a player, it will ignore all the targeting stuff. Like I said, it's purely to offset healers in arena or for making the first kill in 5v5. And for the istant swapping to the second target when the first dies.

And yes, the modifiers are for the leaderless set up. I use keymapping in keyclone to accomplish that.