Part of the mailman install is usually to create to your initial admin user (e.g. an email address and password). This is the password for managing the meta mailman list.
With regards to the mailman list showing up on your front page by default, yes, that is normal. I typically set that list to not be displayed, it's just on one of the settings screens... Just poke around, you'll find it. But first you'll need to sortout your password for the list.