That's how I back them up as well. You are correct that all you need to do is restore the globals.sql, then each "pgdump" file individually. Just ignore the warning when it tries to restore your initial postgres superuser, since it was created by the initdb already.
You probably don't need the "postgres" db at all, since it is just there to allow the client to connect to something on initial install. Normally you don't use it in production.