Heroes of Might & Magic III: Horn of the Abyss

besides Kronverk, are there any other cities with new content? (not necessarily screenshots, just some information)

Well, you'll see the new city closer to the new year; you can see the unit stats for Kronverk in the screenshots – basically, the only one that isn't shown properly is the Sanctuary, but more information about it will be available soon.

are the unit images for the Sanctuary on the new cities website very old?

They are quite old, but since almost all the units are good, they will only change slightly, if at all.