Well yes you can return Games if there is a sticker on the cast take it off or sell it on Ebay or something it may not make you less angry but at least you get some money back also if you have a receipt and it is still valid take it back
2 One nade should not be enough to take down at warthog at least not in halo 4 at least 2 if you or lucky or 3 and yes I am sure I did something if it didn't then lag stuck again
3 Yes halo 4 is flawed but after the huge backlash I think 343 will make halo 5 a good halo game if they don't halo is dead as I don't think fans will put up with another flawed game again.