No, you can search the network just like in LW 4. I haven't used the friends feature yet, so I don't know how well it works

Check the link below & see whether anything helps with your searches.
http://www.gnutellaforums.com/genera...-download.html

If not, you could also try disabling TLS, DHT & Ultrapeer capabilities (tools > options > advanced > super really advanced > performance. Click OK to save the change).

And deleting LW's preferences folder when LW's properly closed. See point 3 here & also point 2 if you've used older versions of LW in the past (there could be a folder in either location).
Fixes for LimeWire
This will change all of your settings within LW's options, you'll have to go back through afterwards & reset things to the way you like them.
Vista users: LimeWire Pref Folder in Vista