BI4.1 SP1 & Audit

Hi experts,

I would to have some inputs about Audit in BI4.1 sp1.

As the audit is something now centralized in CMC ,I try to understand what is really audited.

For example: With Common Events entry, What are the real audited servers. How can i evaluate the quantity of informations need to be stored in my audit database? what is the level of resources consumed, depending of the audit level chosen.

Thank you

Gil