The CC3 Dungeon style is included in CC3+. Just start a fresh map, but use the style "DD3 Dungeon" instead. That will give you the same look with lots more options.

The city is coming together nicely!

Concerning chimneys: The Jon Roberts style doesn't have any, but load up the CD3 Bitmap A default catalog and you'll find some chimneys which fit it just fine.

Dungeon and Floorplan are really pretty much the same. The Floorplan category was introduced at some point, simply because the "Dungeon" moniker wasn't very fitting for modern type maps.

Yes, that is a know limit in the current Hex Grid command.

Remy wrote a macro a while ago which circumvents the problem. I'm attached it to this post together with a sample map.

I don't think any new symbols have been added to the collection since it was released.