Have a look in the version history for the note which is behind the right hand three door menu in the note. You can also find it in note info.
Was it comment icon or the header link icon you clicked
I would contact support using this form and giving them all the information they need. Hopefully they will be able to help.
https://help.evernote.com/hc/requests/new?ticket_form_id=30415233388691&guest=true
There's no real way to build from local files.
It does sound like you've created a new account using a slightly different email address... support should be able to help.
Its not activated by the update but by the server so you have the correct version, just need to wait until the switch is flicked. Shouldn't be long now.
Try logging out and back in again every now and then to see if that forces it.
At some point you most likely clicked on a pop up to "Try Spaces" which creates these notebooks. You can delete them and delete the spaces if you want.
The OCR is pretty good but does need decent clear handwriting to get good results. Any way to approach it would be to transcribe the image as the transcription AI seems to be more accurate than the OCR.
Use one of the backup codes given to you when 2fa was setup.
If you are logged into any other device go to settings and look to disable 2fa from there.
If not only support can help. Make sure you send in the support ticket from the email connected with your account and you should get an auto response pretty quickly.