davej

It is not necessary to have a greyscale image to use the "K only" botton and assign a spot fill color.
It also works with RGB and CMYK images. Whereas in RGB the "K only" results in a mix of R + G + B / but with CMYK the "K only" ignores CMY and show K only – which can be a very different look compared to an RGB + applied "K only".
 

I don't know if this possible as I am new to this but in InDesign I used to import bitmap files at 300+Dpi and then you could colour them to suit and set the transparency of the bitmap as required to obtain a 'greyscale' of the colour. Otherwise you will need to change everything to vectors in the correct pantone colours. You may also need to check separations for anything that overprints. Black may print as an overprint, which isn't always desirable. 

It seems only possible using APublisher, importing the image as greyscale, clicking the option "K only" in the context bar, and applying a Pantone to this image.
I don't understand why the usuall fill layers can't behave the same way... it would be usefull in AD and AP. 

Best print quality would come from 2 Pantone colour job, but then it would be easiest to achieve if logo and bg graphic were vector art. Your company should have the logo as vectors (incompetent if it is lost) and background do not look too complicated either.
Doing pixel images with Pantone is at the moment complicated with Affinity (and I am not sure it can be done).
It is somewhat a matter if the company cares the looks; also if this is digitally printed Pantone does not matter. The form though looks professional enough so I would presume it needs to be done with 2 Pantones and right.

In addition to the red eye that is used to hide or show overflow, if you have View > Show Text Flow ticked, stories with overflow will have two extra round red markers on every frame, when unselected. These markers disappear if there's no overflow, and turn into the triangular flow handles (which will also be red for overflow) when the frame is selected. We appreciate that a proper pre-flight check and UI is needed, but in the mean time it's easier to look for these red markers than it is for the red eye.
(I forget when the overflow markers were added, but it was likely after this thread started so the early replies don't know about them.)

This looks better and clearer.

See the character panel for single char adjustments.

You should be able in Publisher to adjust that single circle character, e.g. select it and adjust it's position and size accordingly to your needs. That should also be applicable to some own paragraph style then in Publisher, so you just have to assign that style on consecutive lines etc.
Related to the export, if you export with embedded fonts (though I'm not sure if Publisher in the meantime supports embedding fonts in PDFs), or if you raster the text (not sure you want to since it gets a bitmap then) before exporting as PDF, then it should be part or glued into the exported PDF file. - However, if the print service has the used font, then it shouldn't be a problem here.
 

It might be easier to do with a font which already has build-in support for certain glyphs (like a circle, rounded rect, rect etc.). See also Unicode Character 'BALLOT BOX' (U+2610) and supporting fonts. This way the glyph and characters are sized accordingly and can be easier layed out.
BTW for the indented line options (glyphs) it might be clearer to use rounded rects as checkboxes then instead of circles too.
See also (Arial Unicode MS): Unicode Characters in the Geometric Shapes Block

It's intentional. In general you can put multiple characters into that field. For example, ---->, or [•]. You can also replace the tab with a fixed space. So we don't try to guess what portion of the text you want to delete.

You can adjust these settings globally (for the entire user account on the Mac) from System Preferences:
https://support.apple.com/en-us/HT202319