As far as Vinny goes, apart from what I believe to be a totally unrealistic view that he could rebound into something overall good, best use of him is to flat-out use him as more or less a PP specialist. When he's set up on the PP he still has a bazooka of a shot and if he's on the PP there's really no need to worry about his defense or backchecking. Just set him up as a turret, a la what Washington does with Ovechkin on the PP to an extent.
Trying to make Lecavalier useful at ES, again presuming his play this preseason and last year all keeps on going, is a lost cause I think. He plays the most important forward position defensively and regardless of where he is he's still a player out there and if he's a liability defensively then that's an advantage for the other team regardless of who his linemates are. It's only compounded by our lack of top D. He shouldn't be at C because he can't win face-offs or play defense, he can't play wing because he says he can't play wing and I guess is a bit worse there. It just won't work, doesn't matter who his linemates are.
If we had a D like Pronger back there I guess we could just throw Lecavalier out there and expect for his liabilities to be covered for to an extent, but as is there's no hiding it really. So just put him on the PP as much as possible.