Any ETA on when we will be able to withdraw from the viral exchange?
What are you talking about? viral exchange?
is there any campaign for token gravity or mercury ?
No there isn't any campaign right now. I'd think the last campaign was on late 2016.
is there any kind of no or masternodes for darcos gravity or mercury ?
I'm not sure about this, it's much better if you will ask it directly on their discord channel -
https://inviteme.darcr.us