No JAN certainly do not control all the oil, that most of the oil fields are located in Kurdish controlled areas should give you a big clue there.
Again, no one is calling for the West to arm JAN.
Also, just because people are working with/for JAN and similar groups, it doesn't necessarily mean they support all their aims. This is a time of conflict, people are just getting by.
To answer your question
"Do you think if Assad was gone tomorrow that they would be giving these up either to the merchant class or the FSA?"
It's not about giving things up, it's about not being able to maximise profits when you're working in isolation. Being successful in business means making deals.
You don't seem to understand that while most Syrians are religious, they aren't salafi, it's not a popular ideology there. People are tolerating certain groups now, because they need them, not because they share their aims. Again, once a group or movement has little to no support base they will be finished.