I have a few questions about shortBTCD
OK, I understand that if BTCD goes down by 10%, shortBTCD goes up by 10%
If lets say I have 10BTCD what is the equivalent of this in shortBTCD in order to receive for example the -10% loss of BTCD ?

Is shortBTCD in an exchange? Where do I sell/buy/trade it?

To buy it for the first time, do I have to send NXT ?