1.a. For Cloud Account Recovery, you need to open a Support Case if you are unable to use the standard password recovery mechanisms of the Support Portal (the password is shared, so you should try logging in to http://support.cambiumnetworks.com/).
1.b. For On-Premises, in the Console navigate to Maintenance > Recovery, and you can select a one time Application Account Recovery password. This is also detailed on p. 206 of the User Guide.
2. If you have exported the full configuration, you can import it into a new installation of cnMaestro, but you need to make sure the version is supported (if it is very old, then it may need to be imported into an interim release).
3. Not sure I understand this question.
4. Are you asking if you can configure a Gmail SMTP server for email notifications?
5. We don't currently have Telegram on the roadmap.