Yes, the internal traffic between two VPS, a database server, and a web server are all counted in the bandwidth usage of your VPS.
Even if you use a private IP address for internal traffic, the bandwidth will still be counted for that VPS.
Yes, the internal traffic between two VPS, a database server, and a web server are all counted in the bandwidth usage of your VPS.
Even if you use a private IP address for internal traffic, the bandwidth will still be counted for that VPS.