[color:"orange"]Question 1: We don't know who was "made" the catacombs, do we?"[/color]

I vaguely recall Lanilor(?) saying that the catacombs were there before the town, and that Mardaneus entered soon after the founding of the town, then ordered them sealed, never giving a reason or describing what he found.
I don't remember if it is mentioned in game whether the necromancer made the catacombs or moved in later. He started experimenting with his living servants, so the catacombs may have started off as a family mausoleum below a mansion, or something.


[color:"orange"]Question 2:I have some doubts about Rivertown. I would think that everything west of the river is called Rivertown, and not only the commerial center where the merchants are. And then the commercial center is called Ars Magicana...[/color]

I took the whole first map area to be Rivertown, east and west of the river.


[color:"orange"]Question 3:Where are the Council of Seven hall and the Wastelands actually situated? It could be usefull to have the ingame teleporters map, but I didn't find it yet...[/color]

The marker for the council hall teleporter is in the north west part of the map, partly obscured by the mountain range. I don't know if that gives the rough physical location, or if the marker was just stuck in an open area of the map.


[color:"orange"]about the Wastelands: they aren't actually inhabited. there are a few houses in the West but that's it.[/color]

The deserted town would have been inhabited if the publisher had not rushed the release of the game, forcing Larian to cut back on the ending.