Unlock every cosmetic in the game only whilst the mod is active. Removing the mod will take off the cosmetics you didn't own. (This is a good thing!!)
Want to get the cosmetics legit? Just turn off the mod and you will have all of your previously owned cosmetics. (They won't be equipped by default unless you never took them off).
No, you can still get achievments, it will also say you got this cosmetic by unlocking X achievement but don't worry, disabling the mod will make it go back to normal.
Yes it does, it only unlocks the cosmetics for you, it doesn't affect other players. I see that this gives no advantage and so I don't see why it would be banned, but use at your own risk.
If you want to support me, you can check out my website(s).