using google analytics to track user-wise information

What is the best option to track user wise analytics? I am looking for google analytics along wit开发者_如何学JAVAh per-user reports.

some questions:

1) was using custom variables to track the userId and was able to see the report in Visitors -> 'Custom Variable', any way to see the same on the content report. There is an option for 'user defined variables' but that is not populated.

2) is there a sandbox for google analytics. searched for it but it seems like the only option is to serve the file from the local machine (to check the tracking gif) and to create a separate tracker so as to not pollute the production data with testing. The lack of sandbox seems kind of a PITA. can check the content report immediately but custom variables takes a longer time to get updated.

3) are http://piwik.org/piwik.org or http://mnutt.github.com/hummingbird/hummingbird any good?

4) what is the best way to track per-user interaction on the site, can suggest a better alternative to google analytics. Realtime is not a requirement. Wanted a hosted service as i do not want to host a server and also do not want to go into the trouble of parsing the logs - but can do it if it is easy.