There are onion domes in the City Domes issue of the 2018 annual if you want domes to add to other styles. They're based on Saint Basil's Cathedral in Moscow. There are also plainer onion domes from other East European churches in that set.

The rooftops are pretty complex, but if you want to make complex roof shapes the House tool is your friend. It depends on how much detail you want to get into and how much time you want to spend on each building.

You will almost certainly do better if you don't use the parchment background, but at the same time sheet effects will be applied to the dashes themselves rather than the edges of the polygon, so you may need to make the background white. That will work if your blend mode is set to multiply, as the white will vanish.

Hello rosemarieklien :)

Julian has already provided the link to the blog breakdown I did of that map. Thanks Julian.

If you have any more questions just ask away here.

Yes, that's right. Watabou could give you the basic map and then you could either insert the bitmap export from Watabou into a city map of your chosen style in CC3, or get hold of the 2020 Cartographer's Annual and use the January "Watabou City" which provides full instructions on importing the city directly in a usable state to CC3 and the mapping style to work with it.

If you are looking for a random city generator that can do all of that try the Watabou one here. This is the generator I mentioned in my comment above. You could either print them directly from the Watabou page or use them as base maps in CC3. The 2020 annual would be a good buy if you decided to do that.

Unfortunately, towns and cities do take a long time to map because they have a lot more detail than overland maps and cover a much larger area than a dungeon map.