Are TimeMachine backups password protected?
Not by default.
By default Time Machine Backups are not encrypted. They are stored in a sparse bundle disk image with the name of the computer which the backup is from. You can open this image and browse it without a password.
You can easily enable encryption for Time Machine backups if they are connected via USB/Firewire. It's more complicated if you access your backup disk using ethernet/Wi-Fi. How can I enable encryption for my Time Machine backup?