No it is not illegal as long as you do not try to make any money from it.
heck yea
No, if the person who owns the game allows it.
No
Yes. People have made a lot of mods for video games Pirating: No.
Yes and no. In a way, you bought the right to play the game that you payed for. The game should be available for you to play as your heart desires. So we can say the morally you are not cheating the...