Java EE (Java Enterprise Edition) General Discussion

I'm confused after reading the description and example written using Xerces2-J, dom4j, JAXP.

We can't use JDK 1.5 which come with Xerces, isn't it? And dom4j is a modified/enhanced JDOM API and even Hibernate can use dom4j API.

What is the difference between them? Is it enough using JDK 1.4 built-in library functions? (Only javax.xml.parsers.*, org.w3c.dom.*, org.xml.sax.*)

Which is the easiest and fastest for:
i. generating XML from some java objects e.g. ArraryList, String?
ii. reading XML, validating against schema and saving to database?

Also I don't know what the comparison of the APIs is for:
http://www.sosnoski.com/opensrc/xmlbench/results.html

Thank you!