Well for mac osx it's easy for us (so to speak.) lol
If you want iTunes to import the songs automatically go to LW's prefs>iTunes>Importing & tick enable & press apply.

If you want the LW playlist to show in iTunes then: 1. Go to LW's prefs>iTunes>Sharing & type the name you want to use (you can also do that in iTunes.) And tick the option Share my music & press apply.
2. Within iTunes, I'm not sure if you need to do anything here unless you want to share on a network. But you can go to iTunes Preferences>Sharing & tick Look for Shared music. The other option I think is for sharing your playlist from comp to comp.