Display Grid On Printout Or Exported PDF or Image

I've searched for print and grid and have not found anything on this - but my Google-fu does run short (mostly when the answer is obvious).

Is there any way I can make the grid show up when I print from LibreCAD?  Or force it to display when I export a PDF or an image?

I don't think so.
A workaround could be to draw your own grid on a separate layer, as points or as lines in a very light colour. Could be re-used in other drawings.  

Excellent idea!  Thank you!

Would there be an easy way to change the scale of the grid quickly and easily?

For printing it will be scaled like the other elements anyway.
If you mean changing the resolution, density, you can use modify - scale of course. But it's not that quick and easy. Maybe better to have several variants predefined at hand.

Yes, I think you're right.  I'd be better off with multiple grids to use.  Thanks!