Technically, you can just chuck any template into @Templates\Cities\Floorplans to use that style. Note that it does look for certain tools to set the fill/sheet/other properties of the walls/floors it draws as part of the floorplan (The Wall, Default and Floor, Default tools), so if those tools aren't present, they will just use a solid fill instead, but the shape will be drawn, so you can just use change properties

I think you need to brush up on your conversions. 30 km is about 100,000 feet. Of course, you wrote 30k kilometers, which is 30,000 km or 100 million feet.

That's way to high. You shouldn't go higher than 40000000. You can easily calculate that number yourself. Take that 6000x6000 that you manage to export, multiply that up, and you have 36000000. That's your practical limit for how much large a map export you can do in a single pass. If you set the ppp value higher than you can handle, you'll end up making your max possible single pass size your absolute max as well, because CC3+ won't be allowed to go for more than one pass.

The vegetation for DD3 is found on the Skirmish button (the last one).

The lines have a fixed length. They are then scaled based on the width of the drawing, so if that doesn't match the ratio, they don't end up being long enough, or alternatively, too long. The new map wizard doesn't distort images, it always scales them proportionally. ()