1. Give me a link.
- here is same addon and works.
3. That isnt addons_lib.php issue if you copy it to /includes dir. It is necessary just like all files in my mod (for PP earlier then 1.5).
4. What is funny I see gravatars randomly, maybe gravatar.com have some problems (IMHO yes coz after login I see - "Gravatar.com is Down for Maintenance").