last_dovahkiin

So I want to make two lines that "follow" one-another, like picture below. I want to make border lines for my map. The image below is created by drawing one solid color line, and another with either dotes or lines - but the problem is, while it is easy to follow one line with another on the small scale or when the line is straight, it is problematic to follow it when it is curvy. Is there any way for me to simultaneously draw both lines, or at least to draw one and then have some plug-in do adjust another line to first one?

Is there any way to add custom line styles? Like on this image for country borders. Also, is there any way to select an area from either side of dotted line? It only works with full line, but sometimes I want to draw dotted line and select just area on one side of it, and it automatically selects everything since he is not registered line cause of "holes" in it.

Is it possible to have filled in without lines or selection? For example, like in map on the image attached. I would need this for historical map making for areas where I'm not sure where the border is. I know that you can use "Selection" tool and fill in, but it's not "as smooth" to make outline with it as it is with Paintbrush. So, is there any way I can draw lines with Paintbrush, fill the selection and delete the line? I could "overwrite" line with erase tool, but that would too create "space" between 2 filled in areas, and I want the effect like in image bellow - 2 euros without hard border that are touching each other.