Regarding Ultrapeer shielding -

The message about the ultrapeers - Means that you will be shielded from the bulk of the search traffic on the network. I believe that Limewire is using something called QRP (Query Routing Protocol)

Your computer sends a list of files it is sharing to the ultrapeers you connect to. These ultrapeers use this list to determine what queries should be forwarded to your computer

Hope this helps.

http://www.leeware.com