Re your queries
The Third Party Backup option will be appear once its been enabled through:
- Installing one of the apps (AWS)
 Amazon S3 BackUp App
- Enabling it in the config file for Dropbox
 https://frappe.github.io/erpnext/user/manual/en/setting-up/articles/setting-up-dropbox-backups
Yes you can, by configuring a cron job coupled with the bench backup command
Again you can do this using the bench command and you can find the details here. To note if you are using Virtualbox VM, the networking side of things will be a challenge if you are not familiar with Network Admin.
https://frappe.github.io/frappe/user/en/bench/guides/lets-encrypt-ssl-setup.html
Hope this helps.