Conditional to open context menu

How to:

  1. When I right click onto a URL that has a condition such as having a string of .PDF in it, context menu will show and have an option of ‘Open with…’ to open by a specific app which was declared before in settings tab.
  2. How to develop a plugin combination of ‘Ctrl’ key and left click to open the previous type of URL in (1).
  3. List of all URL to local files in the beginning of note with number or name like
    :: .
    Afterwards, when I want to refer to one of these files, I just refer to the corresponding name.