When you download an album or track from the iTunes Music Store, the album cover art and the name of the artist, song, album names and genre are embedded in the files.
To change or add more information you need to right click on the track(s) you wish to update by selecting "Get Info" or select the same option from the drop down File Menu. Then select the appropriate tabs to update and change.
To get the lyrics in to the songs you still have copy and paste them from a song lyric web site e.g. [www.lyricsmode.com or www.elyrics.net] or your preferred web site.
Some artists have now started to include lyrics, videos and photos as part of the new iTunes LP setup for example "Queen". I downloaded Queen - News of the World - 2011 Remaster and it gives you the lyrics.
Your iTunes software must be the latest version (10.4).
Sometimes you get a 'Digital Booklet' with complete album downloads but again this depends on the artist and the record company. I downloaded the 'Foot of the Mountain by a-ha' album which gives you a Digital Booklet with lyrics.
As for the "Get Track Names" being greyed-out and not clickable, this is a hit and miss feature which has a mind of it's own.
iTunes assumes that you don't need to get the track names if you all ready have them. If it is greyed-out then just 'Get Info' and insert the track names.
Maybe another person will shed more light on the 'Get Track Names' feature but I've never had any problems with it. Just be sure that you are online because iTunes gets its' Track Names from the GraceNote Database which it can only access if you are online.
Hope this information is useful to you.
F.