What is the difference between x-pass and toreando?For me x-pass is very similar to toreando. I think of it as baiting a reaction with my foot between opponents leg and when he goes to grip it, I start "a toreando" ... most likely ending knee on belly or blocking his hips with my leg
In Polar JJ toreando pass is after standing up from closed guard and opponent has his feet on your hips. You grip his pands and push on knee down, step a little sideway to loose the other foot and pass by pressuring opponent with your shoulder. Your arms are making X! - like in x-pass :-)
Here is an important tip - don't let your opponent bring his knee back in by letting go of his pants too early.
Where to grip opponent?There are many options on where to grip opponents legs. First inside or outside? With inside grip it's easier to split opponents knees apart and little less danger of spider guard...maybe. With outside grip it's easier to push knees to side and just come forward.
Also do you grip knees, ankles, pands or legs or knee and ankle - cloth or body?
(I'm not going to answer these - it's what you are after - or what do you want opponent to think that you are trying to do.)
Push his legs or run a round?Why would opponent stay on his back if there is no pressure? (Maybe in competition jiu jitsu people prefer to play guard, but it's not a very safe place to be in martial arts thinking.) So if you don't have pressure, opponent is very likely to sit up and atleast make a grip on your sleeves. One way of passing is pushing opponents feet to mat and going a round his knees and there are counters, but there are counters to every move.
I like Ribeiro's way of waiting for a reaction - it gives you a split second more time to work your move. Here is Leandro Lo explaining his take on toreando.
End up shoulder on opponents belly or knee on belly?In a way I don't care. It's a pass. BUT more important is do you have control of opponent! Can you progress from your position.
This is not a very complete study of toreando pass, but for me here is a lot of details to think about. Biggest take a way is "bull fighting" - it's not paint by numbers, but reacting to opponents moves.