wallhack or something doesn't magically give you better aim skills so you still suck.
They let you know where the person is and you can have your crosshair put on that spot, while others need to try and cover their whole sector. Not to mention if hidden, crouched under.
What the forget you speaking of?
Depends on the game and on the hacks. It can be very funny sometimes (Smash Bros. Brawl)
Yes, hacking is/should be
always acceptable on SINGLEPLAYER. I am talking about multiplayer over internet with other people.