Celestial Heavens visitors may remember an old news entry dedicated to the official Russian Heroes V forum and a special thread where Larisa, a Nival representative, answered users' questions.
Recently, answers to some more questions have appeared. The complete Q&A has not been translated from Russian, since a lot of answers are just "we haven't decided yet" or "it will be revealed soon™". However, there was also some useful information, for example:
Some light on the Heroes V magic system will be brought in 2-3 weeks.
Steve Fawkner, the creator of the Warlords series, is acting as a game mechanics consultant.
Archers lose the area attack ability after upgrading to Marksmen.
Sometimes spells can fail (wasting mana) or turn against the caster...