First and foremost congratulations for the extension. I installed it and I am on the third day of tests and it does exactly what it says, and it helps a lot.
a) I understand that the notes do not affect the email itself, so it can be sent/forwarded one or multiple times and it will not be shown anywhere. However, is there any possibility that the recipient of a mail with a note knows that there was a note at all? (i.e a correspondent sends me a mail, I write a note and a couple of days later I reply the mail -with the original mail inline-. Can the correspondent know there was a note?)
b) where are the notes kept? Can the location be changed?