Analog sticks are always on the left side, this is because you want your right hand for the buttons, which are more important.
Depends on the game. But in most cases I don't think you can really weigh one more than another. Would you rather go through Super Mario Bros without the D Pad or without the A and B buttons? Would you rather play an FPS by standing still and constantly firing straight ahead, or by running around without picking anything up or shooting anything?
You can wax on, wax off all you want. I'm still kickin' your ***.