Nope, you can only sell your stuff from a mall but in order to do that you will need to buy a shop in that mall for a lot of money. Better to TT cheap stuff or if you wanna play eco sell to other players for a bit more money.
No, unless you deal directly with the shop-owner.
A new item would need to be created, the opposite of a shopkeeper pad which would allow the owner to place orders for items (like can be done through the auction).