You've heard type 2 diabetes referred to as "insulin resistance". Well there are generally two types of meds doctors prescribe for type 2's. They are 1) Drugs that nudge your body to produce more insulin and 2) drugs that break down your resistance to the insulin your body produces.
Metformin is the latter; it works to break down or reduce your "resistance" to insulin, thereby making the insulin you are manufacturing in your body work better (more efficiently). Hope this helps.
No, I don't believe that is the case. As I understand it, Metformin's main mechanism is to stop the liver from releasing excess glucose into the blood stream. This works because the liver stores excess glucose for later use by the body.