Are there any examples

In the examples page you can find a set o basic examples that will shou you how to use the Http Service and/or Web Container.

Can I change the version of Jetty used by Pax Web?

Yes, you can starting with version 0.4.0 of Pax Web. Just deploy the jetty bundles you want to use. Pax Web is proved to work with Jetty 6.1.3 -> 6.1.7. Also note that if you are going to deploy a different version of Jetty then the one embedded is better to use the Pax Web artifact that does not embed Jetty as you already have jetty bundles. See next question for details..

Why are two pax web artifacts? (pax-web-service, pax-web-bundle)

The difference between the two artifacts is that pax-web-service embeds Jetty and pax-web-bundle does not embed Jetty. See details.