How will be implemented card trading? Is it possible? Can player exchange cards or they have to pass through a market where selling/buying them?
All cards are linked to items, so there probably won't be individual card trading. I would like to see item trading implemented, but based on the commit messages on https://twitter.com/RudolphoCH I haven't seen any indication of it.
With the sheer volume of items we'll be looking at in game (and the completionists among us) I'm sure there'll be a trading feature eventually, it's just not a priority for getting the game into Beta.