Is There A Way To Edit PDF, JPG, Or Excel Files In Agenda?

[trebso]

Not sure, as I tend to only add files to Agenda as reference documents. Files I want to edit live in the Finder for me, but I often link to them from agenda. To add a link, rather than the actual file, control drag from finder to note:

Link to file vs. Create Copy on Mac

If you hold the Control key while dragging in the file it will create a link instead of making a copy, just as you would like to see. Keep in mind that that link then only works on the machine where you dragged the file in for obvious reasons.