1) The null is just the name of the session factory. Naming it is not necessary.
2) You will want to use something like c3p0. Take a look at https://community.jboss.org/wiki/HowToConfigureTheC3P0ConnectionPool. If you set those settings, it will turn on c3p0.
3) You are setting driver.class
but it's driver_class
4) Autocommit false means you will need to manually commit your transactions. This is the normal pattern.