If all you need initially is for all the walls to be identical for both floors, just copy and paste the walls of your first floor's drawing to wherever you need them, using |CC2COPY| .

If the doors and windows aren't the same on both levels, do this before you add any doors or windows.

If both levels will be in the same map, you can just use the straight copy command. If you're setting up two completely different maps, one for each level, then use the "Copy to clipboard" option instead, because the basic copy commands won't copy the selected items to be pasted in a different file.

The water lines problem looks to be one of the classic issues with too many nodes too close together, in this case because the water drawing tool is set to not extend beyond the map border, and as a smooth drawing tool, it will automatically put a pair of "Corners" at the map border to create the straight line there. A Corner is basically three nodes very close together.

A quick check suggests you should be able to solve this by using the "Advanced" button for the water drawing tool, unchecking the "Restrict to map border" box and then save the tool. Then redraw your river, making sure you draw the ends a little way beyond the top and bottom map edges. DO NOT use the "C" = "Corner" option, just add a few nodes and make the ends of the river outside the map border a bit more rounded, with fewer nodes close together. The screen should hide this once you're done (or if not you can use the COLLAR commands to create a new, larger one - use COLLARDEL first to remove the existing screen, and then COLLARAUTO to add a new one - if I've remembered that right).

Hopefully, that'll cure this point at least. Good luck!

Yes, CC4 is a work in progress. As CC3+ users, we have no definite information beyond that, so far as I'm aware. It will doubtless all be revealed in due course!

This blog posting by Remy Monsen might be worth reviewing, as it will allow you to create an image of whatever you wish that looks as if it's been cut into the surface involved.

Ctrl + F should do it, I think. It's the same command as Tools -> Drawing Aids -> Toggle frames using the drop-down menus, because what you're doing is toggling the frame (thin white line) options to show where the nodes are on a line.