can you suffocate someone so they pass out but not die?!

Well, yes, you can, but it would be hard to control and hard to know when to start reviving them or whether they could be revived. Way too risky to try. People will pass out from lack of oxygen, and can be revived when oxygen is administered, but if one is strangling someone, or holding a pillow over their face, they will likely kill them in the process through the force exerted and the victim's attempts to fight back.

Yes, but like Kateg said - it's risky. You could do irreversable damage.

Either way, for heaven's sakes please don't try!

Yes. It's like when you hold your breath you'll pass out before you die.