Home Sharing does not transfer star ratings or playcounts for music.
By default, i Tunes organizes albums based on the name of the album's artist.
I am so used to how I have my music organized with this program that I ended buying an external hard-drive and putting my library onto it.
The downside is that I now have my i Tunes library on my internal hard-drive and my DJ'ing library on my external HD.
Consolidating your library will take all of the songs you have imported into i Tunes and copy them into an i Tunes specific folder (usually a folder called "i Tunes" under "My Music" in "My Documents").
To rid your Mac of music, you may want to consider i Tunes Match, which allows you to stream and sync your library through the cloud.
If you’re the kind of person who likes to rate songs, you can remove unwanted tunes pretty easily. If you want to find missing album artwork for songs in your library, click File Library and select Get Album Artwork. Sort your songs by name and look for any that are called unknown or untitled.
You could use Tunes Cleaner via the Mac Store for this, but it comes at a cost.
If you have a small amount time, however, you would be better served with this tutorial.
Your i Tunes library is a database that i Tunes uses to organize your media.