Regarding the multiplayer question...
This game has a real time elements, like seeing your opponent every move. Every multiplayer has a invite/create game/search and a join/comply/search on the other side. So our game is not different form that. Leave alone the whole technical stuff, It always comes to player actions - meaning their will to play. No matter if it is real time or turn based. Regarding you commitment into playing a match or doing in causally without time limits rises the question about your opponent waiting for you to action and allowing him to play another game/match in the same time. As this game relies on heroes and levels (not like chess for example) it really looks inappropriate to me.
As an old CCG players, you should really consider inviting your friends, who like to play such games in multiplayer. Most of our players play in single player. They like the campaign and really don't like playing against other people.
Players in the lobby are online but not playing. Many just ignore the challenges and yes the players from the web usually leave their game clients running for days in a different browser tab


Now here are some current numbers for the US server:
There are about between 300 and 500 ranking games daily.
There are around 7500 single player games every day.
There are around 600 player visiting this server daily.