What determines how much structural damage a stack does

If you want to know the version of the game, you can find it in the main menu in the lower right/left corner.

However, be aware that Steam does not patch Heroes 6.

It's patchable through the Ubisoft Installer application which in turn is installed by Steam when it enters the prerequisite stage of the game installation phase. Whenever you launch HOMM 6 via Steam it automatically launches the Ubisoft application which checks if there is a new patch.

It is an either/or choice, as reputation controls the class of your hero. Once you have enough Blood points or Tears points, your hero changes class and gains a new ability. You then get the chance to fill the points bar a second time (but only with the same type of points), which gives you an advanced ability for your class.

As in previous Heroes games, each faction has a might based hero and a magic based hero. In Heroes VI, each faction also has a might or magic based Blood hero and a might or magic based Tears hero, for a total of six classes per faction.

Shamelessly stolen from the Heroes VI website, the following table lists all the hero classes available:

Haven

Name           Type      Reputation
Knight         Might     Neutral
Cleric         Magic     Neutral

Paladin        Might     Tears
Confessor      Magic     Tears

Vindicator     Might     Blood
Inquisitor     Magic     Blood

Inferno

Name           Type      Reputation
Heretic        Might     Neutral
Warlock        Magic     Neutral

Hellcaller     Might     Tears
Demonist       Magic     Tears

Chaos Lord     Might     Blood
Pyromancer     Magic     Blood

Necropolis

Name           Type      Reputation
Ebon Knight    Might     Neutral
Necromancer    Magic     Neutral

Bone Guard     Might     Tears
Embalmer       Magic     Tears

Death Knight   Might     Blood
Reaper         Magic     Blood

Stronghold

Name           Type      Reputation
Barbarian      Might     Neutral
Shaman         Magic     Neutral

Chieftan       Might     Tears
Earth Shaper   Magic     Tears

Warmonger      Might     Blood
Storm Caller   Magic     Blood

Sanctuary

Name           Type      Reputation
Samurai        Might     Neutral
Monk           Magic     Neutral

Shogun         Might     Tears
Tide Master    Magic     Tears

Warmaster      Might     Blood
Flood Conjurer Magic     Blood