A Nival representative known as "Old Boy" continues to post answers on the Russian Nival forums. Here is a summary:

  • The ability to sell artifacts was considered, but they ran out of time. It will possibly be implemented in the future.

  • There is nothing wrong in giving heroes starting abilities that prevent them from reaching the ultimate. Ultimates are meant to be very hard to get, and only in ideal conditions.

  • The Death Knights will not return to the Necropolis town.

  • Vampires drain their victims' "vital essence" instead of blood, which explains why they can drain life from undead. In case of undead, the vital essence is the magical energy that keeps them going.

  • It is possible that the paperdoll will be implemented later, but it isn't known for sure.

There's more info in the forums. Have a look.