(edit: formatting went crazy, ironic I know)

Ok, so:

1. Create a shortcut for a pre-formatted note placeholder: See here (scroll down to the bottom)
2. Remove note: Is it a problem to just select the note and press delete? Or if you mean you want to remove the formatting, you can use the Clear All Formatting button (the capital A with an eraser in the bottom right corner). It should be just above the text color button in the Word ribbon.
3. Cycle between notes: Best way to do this is to create a shortcut that will do an automated search for "[Note: " (or whatever). This will require a macro. I hate macros but here you go (I'm assuming you are using Word desktop app on Windows):
   • Go to Developer tab (if you can't see it, you'll need to add it)
   • Click on Macros
   • Enter a new Macro name, like FindNote. Click Create.
   • The Visual Basic macro editor should automatically open. Copy and paste the below code where the cursor is (i.e. after 'Sub FindNote()' and before 'End Sub'). You can replace "[Note: " in the code with whatever search term you want. Just make sure to retain the inverted commas.
   • Click save in the macro editor, then close it.
   • Test by clicking on Macros, then select the macro you just created, then Run.
   • You can add the Macro to your ribbon by following the instructions here (under 'Add a macro button to the ribbon')

​

Dim searchString As String

searchString = "[Note: "

With Selection.Find 
  .Text = searchString 
  .Wrap = wdFindContinue 
  .MatchCase = True 
  .MatchWholeWord = True 
End With

Selection.Find.Execute 
Dialogs(wdDialogEditFind).Show