if i'm using spring to manage my hibernate sessionfactory, and i configure my datasource to point to my tomcat6 jndi datasource w/ c3p0, is there a need to setup hibernate to use connection pooling via Hibernate's C3P0ConnectionProvider? or will it automatically use c3p0 if it is setup in tomcat?

also, what are some good configuration properties to set for a site expected to grow? im going to be using mysql 5

The c3p0 properties will be ignored in Hibernate if you're using a Tomcat-provided DataSource. You can remove them.

As for the other question, do some googling for MySQL tuning, etc. The best thing for you to do is create load test scripts and establish a baseline before you do any tuning at all.