Password: whatever you set it. You can reset the password in the MySQL tab of MAMP.
Database: Use the name of the database you just created.
Also, you need to edit the $tmp_path and $log_path to add the path to your website folder. For example, if you put the website folder in the Sites directory in your own user account, then the path is
/Users/[user-name]/Sites/newsite/logs and /Users/[user-name]/Sites/newsite/temp
Use phpMyAdmin to search the wp_options table for the domain name of the live website. You should get two results. Change both of these to your local domain; in my case, newsite.dev