Now when you say leaping... you mean jump and then slide tackle or a wall bounce into a slide tackle? In which case, I don't see why this combo can't be done.
Edit: Sorry, just actually understood what you were asking. That's a good question. I think we'd have to wait to test that out in game to really see. Would be interesting to see someone wall bounce out of being slide tackled, though.
Nope and nope, simply that a player can leap over an enemy player, who is trying to slide-tackle him
Edit: Just saw your edit, nvm.