Hibernate version:2.1.6

I have Tomcat 5.0 and multiple webapps. Several of the webapps share data in a database accessed through Hibernate.

What are the ramifications of putting Hibernate and required supporting jars in /common/lib/ ?

If Hibernate is in /common/lib/ I assume we need to put hibernate.properties in /common/classes/ for the shared access, but I don't see how hibernate.properties can be used to configure more than one source.

is there a best practices document? wiki?

Given multiple web applications in tomcat, how can we

1) Use One Session Factory?
2) avoid use of /common/lib/ common loader?
3) define hibernate.properties for each webapp?
4) if /common/lib/ needed to be the location for hibernate.jar, then how can webapps utilize hibernate.properties as when hibernate is loaded by the common loader the hibernate.properties in the webapps are ignored.