Questions on using a moving gantry style mini-mill...

[Ger21]

I see there is possibly a more useful one called [TOOL_NOTES]

That depends on what you want to do.
For adding a G5x, I think the file notes are a better choice.

For the park position, add the M883 at the start of your tool change section in the post, followed by your pause.

[Davek0974]

Its more complex as usual :)

The park position is only needed on a couple of jobs which need to be part machined then the clamping moved around and the tool changed then the finish cuts made.

There are three options i see tool_notes, toolpath_notes and file_notes - all look useful.
The G5x only needs calling at the start of one particular file.

:)