Man-free leverage, etc.

I teach outside leverage in off coverage and inside in press. There is help to the inside and most of the time I'm willing to give up a "3 yard headache." The key to that is teaching good tackling technique. If your corners are good tacklers, they can drive on a slant and pop the receiver as the ball gets there, hence the 3 yd. headache. If i give up three straight 3 yard slants, I win. Most teams punt. However, in a 3rd and 4 or under, I would go to a press coverage anyway to take away that quick slant. The thinking behind outside leverage is that there is help to the inside. If the corner gets beat to the outide there's nothing but a lot of green to run to. There is a ton of traffic inside. Why are receivers and running back taught to get outside after they break the line? Less defenders. That's why I like outside leverage in off coverage. Again, if I'm in press coverage, I'm trying to take away quick slants and the such and prevent free releases, so I will change the alignment to inside.
As for where the focus is, presnap is in the backfield. In the middle of a triangle made up of the nearest lineman, the deepest back, and the reciever. That way they can see all and try to make a quick read right at the snap of the ball. As soon as the ball is snapped, it's totally on the receiver. I've always thought that while playing man coverage, you have to see the man you're covering at all times. You look to the backfield or for the ball when he looks. And you're not in good body position, if you're beat, you never look for the ball, just focus on getting back into position.
Playing the run is difficult and a corner in man, esp. in press man, must rely heavily on his teammates to be yelling run and alerting him to it, so he can change how he is playing.
As for primary force, it's always a linebacker if I'm in man. I can't rely on a DB to have primary force. In man coverage, his first priority is to cover. I'll have a DB, say the SS, as secondary run support, but never primary. Too much pass responsibility.
I've given you a little bit on each topic. Hope it helps.