If your main concern is music, I must sadly turn you away from linuxmce. As of right now, the music organization and playlist stuff is not very user friendly. Here are some problems I've found with my small music collection.
1.) CDs with multiple artists are split by artist. So, even when sorting by album, each artist on that album gets it's own picture on the giant 3d cube. So, my classical music CD will have 6 entries as there are 6 different artists on that CD. Quite annoying.
2.) The album grabber doesn't let you choose 1 picture for a whole album. each track must get it's own picture, which means you select a picture for every one of your songs. You can get around this, but not using the cover art grabber.
3.) I have yet to find a way to add an entire album to a playlist. It seems that you have to add each track individually.
4.) Playlist manipulation is generally sloppy
Don't get me wrong, I love LMCE, but the music section is not where it could/should be. I know that at least some of those issues are going to be fixed in an upcoming update, so you might want to wait till the next release.
Also, I think that mythtv's audio integration works better than lmce. You could go with an ubuntu+mythtv install. That might work better for you.
You do know you can add a single cover art to one album via the web-admin right.
If you goto web-admin - files and media sync.
Click on your share in the left pane - then click on an artist in the left pane - then click on an album in the left pane. You should now have a list of tracks in the right pane, ignore anything that is not related to music, IE if you have your library set-up in windows as well you will likely see album art small, album art large etc...
So what you do (I have a folder.jpg in all my music folders for each album)
Now that you have the tracks in the right pane - at the top of that list choose edit all files in the list, that will open a new window at the bottom of that list you will browse for a jpg file do that, NOW before you attach the file uncheck anything that is not .mp3 - .flac etc.. so anything .jpg or that is not a music file or the pic will not attach. I did over 700 Albums this exact way with no issues.
NOW one more thing - if you have ONE track that has cover art applied already then the edit all attributes will not attach the picture, what I mean by this is if there is one music file in an album that you have attached cover art to already and you are trying to edit all of them it will not attach the new file - you first need to delete the cover art for that one file and then edit or unselect that one file that has cover art when trying to edit them all.
After the cover art is applied you will still need to edit any attributes per file of course, colinjones has mentioned you can edit attributes for an entire album as well, I have not tried this only for not knowing how LMCE applying attributes will interact with the tags already in the Album. I have all my FLAC files tagged with Mp3tag so other than having various artists on certain greatest hits albums (which I fixed in media sort by searching by album - then greatest hits - then renaming that to IE Neil Young Greatest hits or Tim McGraw Greatest hits for all the songs from that G.H. Compilation) there was no problem and all my Album Names, genres etc are well placed in the Audio UI and in fact are fully searchable. I still get the album art per performer if browsing by artist which would be normal as you attached a covert art to that song in that album and that is the artist on that particular song. It would be the same if you had the same performer on a different various hits album. It would display a diifferrent cover art for the same artist on that specific album with that specific cover art attached.
IE I have Night at the roxbury soundtrack with a dance track (performer's name escapes me) and then the same performer on Miss Congenialities Soundtrack. I have that same performer twice in the UI with one having the Night at the Roxbury cover art and one having the Miss Congeniality sound track cover art.
This also applies to TV shows etc...