You can use the steps above for any field to add a term or word to a field for more than one reference at once but you still would need to do it one group at a time to get the right term or word linked to the correct set of references.
See
In step 2 you would just be selecting the Research Notes field.
I do not see a way to get the data in any other format but you can save tor RTF or TXT then open it in Word to further manipulate the information.