I tried a couple of tests using the "Save As... - Rectangular Section JPG" option in CC3+.

Ordinarily, I use a small amount of antialiasing on JPG exports, generally 30% to 35%, and forgot to turn that off, which meant the export failed! So I tried again with Antialiasing turned off.

I suspect the single key thing is to ensure the final export size is set to for A0 paper, so I turned that up to 119 cm. This is my settings pane:

And then I ran the export. The final file size is about 66 MB, but this is a sample zoomed-in to be 100% and then resaved as an image the Forum will accept (so it's smaller than the true 100%). However, when I was zoomed-in at that level, there was no pixellation whatsoever on the roads. This is that smaller image, but using the above settings:

I think all you really need do is ensure the final image size matches the paper size you want the export for print to be - A0 in this case. Good luck!

Ah, don't worry over it! The physics of crater formation is endlessly being revised and experimented with, like most sciences, whenever something new and unexpected turns up. It's a particularly tricky field, because most of the impact craters easiest to examine in some detail are on the Moon, which isn't a helpful analogue for such craters on Earth, or other places where there's an atmosphere to alter how they look on various timescales, from original impact onwards, or how they can form when an impactor strikes a medium that isn't lunar regolith and rock. First approximation stuff is fine to give a crater that looks like a crater non-specialists can recognise and make use of!

Plus, what you have now will work nicely for both impact and (inactive) volcanic craters - though the latter will work best connected to a suitable mountain-top or area of suitably craggy rock, of course.

So far as I understand it, if you have an MS Office 365 sub, Publisher will cease working in October this year (I think - can't actually recall the exact date now). If you have Publisher on a computer that isn't connected to the Internet (so it was purchased years ago, probably on a disk of some kind - 3.5" floppy or CD-ROM), you should be fine.

I checked around earlier this year when this was first announced, and it seems that the free Libre Office suite (essentially the free equivalent to MS Office) will still open MS Publisher files. I haven't had time to install and check this as yet, but I know the earlier version of their MS Word-equivalent worked fine, and would open MS Word documents, although MS Word (of course...) won't open their files.

I like Publisher because it's so easy to resize the physical page size to fit whatever you're creating exactly - so it's really easy to create and save images, including images drawn in Publisher, to a very precise size. I know you can do this in other programs as well, but I've been using Publisher for decades, so it's much easier that way. I used to create all my maps and diagrams using it 20+ years ago, including for print publications!

GW are not noted for their generous licensing terms; very much the reverse, in fact, judging by conversations I've had with owners of small businesses interested in trying to sell their physical products over the years, and they insist on a huge amount of control over exactly what can be sold, how much stock the business HAS to take per month (regardless of what the business itself knows will actually sell), and how it can be displayed. I can't imagine they'd be any more willing to consider something like this. If they were interested, I'd expect they'd be doing it in-house already.

Interesting broader discussion here. The earliest surviving topographical (known-)world maps tend to show the map creator's country/city in the centre, and many are circular around that point. Wikipedia's Early World Maps page has some useful illustrations in this regard. While that may have had a political motive, there's also an eminently practical one, because then you're able to draw the world moving out from where you started.

Into the medieval period, European maps often had the eastern end of the Mediterranean as their central point, because of its significance for the dominant Christian religion there at the time, and were drawn as circles or ovals out from that area.

If the region around your home site ends up larger and more detailed, that's at least as likely because you'll have more, and far better, information about that area than any other, which you might visit - if at all - maybe once in a lifetime for a few hours to days, in ancient to medieval times. So there doesn't always need to have been a political-patron motive there, significant though that undoubtedly was for some early cartographers.

Maps for planning intercontinental aircraft journeys are still prepared with the originating airport at the centre, and extend out in a circle from there, for instance, to allow the selection of the great-circle line required to reach the destination in the minimum of time, using the least fuel possible.