Free for "developing, testing, prototyping and demonstrating your application" (OTN licence), not for production use.
The installation is pretty simple and there is no special requirement. You can use even MySQL as your database, simply create a Datasource connecting to MySQL
My material for SCJP (2008), SCWCD (2010), SCBCD (2010). About me
If you have a bad day in October, have a slice of banana cream pie. And this tiny ad:
a bit of art, as a gift, that will fit in a stocking