OpenFire Performance Questions?

Hi

is there any document with Open Fire Performance statistics. i am interested to host an IM servcie.can any one answer following questions

Q#1 whats the maximum capacity of users OpenFire can suport ?

Q#2 whats the best Open Source DBMS option with Open fire in terms of maximum useres with top performance.

Q#3 any HW / Server recommendation to host server with Registered 1 Million + usersand and 70-80 K online useres.

Q#4 is clusstering os servers is possible for loadsharing ?

thank you.

Best Regards

Arslan