Try these things:
1. Delete your LW prefs folder whilst LW is CLOSED. See instructions here: Deleting LW Preferences folder in OSX. Be sure to make a note of all your settings before you do this because next time you open LW you will need to re-set your download location, speed, etc.

2. (a) Problems with the search, __ (b) Hostiles List

3. Go to preferences / options & check that searches are set to more than one, both upload & download slots are set to 1 or more. Also see Cant download at all - nothing happens when I click download (click on link)

To find out the version of a program on a mac, go to the program icon at top left of screen next to the apple icon. Choose About LW ...
Under same menu you will find your preferences options. Keyboard shortcut is ⌘ , for most mac programs.

The iTunes issue is a tough one. Generally each user has their own set of iTunes music list when the same location is used for iTunes Music Library (a particular file that will tell iTunes which files to show for the user logged in at the time). Shared LW playlists work on a LAN network but won't work when two users are logged in at different times on same computer.

The hard solution I can think of which I have done for myself in different accounts is, log into his account, re-add those songs you wanted to add for him from the iTunes Music library folder (not re-adding from LW download folder!) To do this is a little mucky as you will need to arrange your itunes music folder via date modified & then check thru the most recent added & choose those you wish to share with him. (You can also add folders.) To add them to his iTunes, open iTunes in his account, then drag & drop your selective files/folders into the Library icon at top of iTunes playlist. This is not a pretty approach but it seems to work. You could also ask this same question on the iTunes forums: iPod - iPhone - iTunes Forums at iLounge