While $50 is dirt cheap for a commission, some people may find it a bit expensive for buying a digital copy of an existing map. I often back various kickstarters, and for that amount, you usually get 20-40 nice maps for that price.

There are no exact features like that, your options are basically

• The Snap grid. Set a rather large spacing, then counting won't be so much an issue. You'll probably want to make sure you have selected a dot type that is a bit large to notice them though. You can set the number of divisions high if you need snapping outside the visible grid. The snap grid is basically the guide feature in CC3+. Remember you can show the grid dots without having snap on.
• Set up a separate square grid in your map. Again, use large grid cells, and add the grid to a separate sheet and layer. You can then freeze the layer to make sure you don't manipulate the grid accidentally, and you can easily toggle it off/on or add a transparency effect to the sheet.
• Use the modifiers. The modifiers such as midpoint, endpoint and center helps you place things precisely.

1. The reason it gets partially cut off during export is the export setting 'Restrict image to map border'. The map border here is the actual map border (a thin line) and not the decorative one. You can avoid this by turning off this option, but it will probably also result in some white borders around the map. You can also use the rectangular section export file type when exporting, which lets you precisely control the export area yourself.
2. This is an issue with how sheet effects work. When they look for the edge to put the glow around, the way this edge is identified is by finding the difference in the image with this sheet on top compared to the one without. But if the pixels on the sheet below contain exactly the same color, as it happening here with the black outline of the trees matching the color of the text, the effects processor sees this as no change, and considers this an edge. Try changing the color of your text to the darkest gray instead of black.

If it is the filters, I think a repair install will fix it since it should replace changed files. Can you try just to run the original CC3+ installer again and it should offer you a repair option. See if that fixes things.

Note that each time you test if things work as they should always test by creating a brand new map, since the map controls which filters to load.

Should be doable with the Mercator Historical or Mercator Revisited annual styles.