Neffster,
1. The Ziggy and XTF Brain v1.2 are very popular. Some other specialized brains are available. Look at the Ultra Hal plugins download page to see some of what is available.
2. You follow the installation instructions that come with each brain. For instance, the XTF Brain v1.0 comes with a Word document explaining many of the new functions. Then go to Hal's menu and select a brain listed there.
3. The forum is the main source of info. Use the forum's search function located on the top right of the forum page. Almost everything you can imagine has been discussed here at one time or another. Read past posts on topics of interest.
=vonsmith=