Creates a unique, persistent monster avatar for each commenter based on email address.
Yes, if they're using the standard version (and I didn't mess up anything).
Yes. Just turn on the Gravatar option in the MonsterID options.
Yes, this plugin provides a replacement widget to Recent Comments (since the default widget doesn't provide the commenter's email).
The gravatar monsters are pretty good but if you want artistic monsters or just want one set of avatars for everyone on your site, then this plugin's for you. Otherwise, sure go with gravatars (just set
&default=monsterid in the gravatar url).