I think this is one of the crazier ones. It's just canola oil! It's the same as spreading that much canola oil on the surface, the spray is mainly convenient because it spreads it out evenly for you without you needing to contact the surface. But Pam gets to put "0g fat" and "For Fat Free Cooking" on the side of all their cans.
That might even be realistic if you are spraying a baking sheet - since you cover the whole thing. But if you are cooking pancakes and spray the pan after each one you get a lot of carbs.
Depends on the pan and pancake. Restaurants use a fair amount of fat in their dough so fat on the griddle isn't needed, if you make your own batter (as opposed to store bought) you can control this and reduce the fat such that you need to add some to the pan. The pancakes will of course taste different. In my case I'm making sourdough on cast iron - I've never figured out the trick to make the first couple not stick (whatever I cooked the night before affects something)