This looks good.

Do I need a fresh ubuntu server to make it work or can it work even if the server is already configured and has some other websites on it?

I have some servers which have wordpress sites. Server is setup using server managers like Runcloud, gridpane, serveravatar etc. Can I still use this on that existing servers?

Can I migrate locally created WordPress and Ghost sites ( built with Laravel Valet) to the VPS using this?