change email address by user in selfservice

[Make66]

When using email address as primary username with
fillEmailWithUsername = 1 validation { username.required = 0 email.uniqueInDb = 1
I guess there is currently no plugin for the user to change his email address by selfservice (which I was told to be a requirement by law)
The plugin must:

• provide a form for new email
• ask for a valid password to allow change of email (optional)
• assure uniqueness in db
• let user confirm email with an system created email message to the new address
• send an email to user after succesfull email address change
• to prevent user of self-lock out, a second email address may be part of the user profile (optional)

There is currently a feature to allow/disallow the change of email address, but not without admin intervention. (as I see it)

I would like to code the plugin and send a pull request.
Which features would you see useful and what should I take care of?