Yes, those dormers come in very handy for hiding unwanted chimneys; done this myself before for a tropical settlement map in the Atlas!

There are some basic geometric vector shapes available in the Symbols => Maps => Other folder, as "Geometry.fsc". These have a fixed colour, however, but if you have the CA62 Geometry.fsc symbol catalogue as well (it's in the same folder), that has varicolor options for the same basic shapes. That might expand your vector symbol options sufficiently.

As for converting colour maps to black-and-white, try adding an RGB Matrix Process effect set to "Gray", and see how well that works. You may need to adjust the full-colour version of the map to keep the contrast sufficiently clear in the greyscale view, but you can turn it on and off as required for exporting images of the map.

Fractal Terrains can export as an SVG, apparently, BUT it's not available as standard, and it may not work properly. There's a trick to it, and caveats - see this Forum post by a certain J Slayton from 2022. Your safer bet though might be using an online converter from one or other of the CC3+ "Save as..." options instead, as Scott mentioned already.

For scaling, the option I use is the drop-down menu command: Info => Distance. Make sure "Ortho" is active, but that "Snap" is off (buttons at the lower right of the CC3+ window), and zoom-in so you can see the grid squares on your image very clearly.

Then use the Distance command to measure the separation between the horizontal and vertical grid lines for a single square. "Ortho" will ensure you're only able to measure in the true vertical or true horizontal directions. (Although both should be the same, sometimes a minor distortion in the map image, especially if it's been scanned, means they're not exactly equal, and your own by-eye estimates can be a few pixels, or more if you're me, out as well.)

That will give you an overall value in map units (feet or metres for dungeon-scale maps, depending on which option you're mapping with) for the size of the grid squares on your image. If that doesn't match with the size of the snap-grid squares in your CC3+ map, then yes, you'll need to rescale the image.

To do this, use the :CC2SCALE: command (button to the mid-left side of the CC3+ window). Click the button, select the image using one edge of it that's free from other entities in your drawing, then click "Do it".

The Command Line will ask you to pick a scale origin (I often use the bottom left corner of the image, but pick whatever point seems best to you), and then it asks "Scale to" with a couple of further prompts. The easiest option here though, is simply to type in the value of the image's grid size, as just measured, and the size you need it to be, the two values separated by either the multiply or divide keyboard options, as appropriate. For example, if the image's grid is showing as 9.4 feet and it should be 10 feet, use 10/9.4 to make your image larger (if you get it wrong, just use the :CC2UNDO: command!).

Then check using the Distance command again, to see if this is now the correct size (or closer to it - sometimes, because of the decimal places involved, it won't be exact, but close enough is usually good enough, though you may need to adjust your CC3+ drawing in places to accommodate any differences). If it's still some way off, just use the Scale command again.

Good luck and good mapping!

Try this advice post on getting bitmap fills into your current drawing.