Hi Jenztech,
1) have you looked at the new Single Sign On stuff?
2) yes, use the URL (see my reply to another of your posts)
3) look at the java source code in the SharePoint pages that have XML form opening buttons for some sample code
4) depends on what you need to do with it. there are SharePoint Web methods to do this - have you looked at the SharePoint SDK?
Patrick Halstead
Project Manager at Qdabra