Good news, I think. The music seems to be in working order. I've successfully played a few different songs and check their file paths and they all indicate that they're on the external drive. Here's how it looks now...what do you think?

Assuming that looks right, I have a few remaining questions. And, by the way, I can't thank you enough...I never would have been able to get this done without your assistance!
(1) Mobile Applications: The "other" iTunes Music folder that I discovered under Music/iTunes (i.e, the one that had the 3 artists in it that we consolidated) was 58GB in size. Obviously it was all those three artists...rather, it looks like the entire 58GB consisted of a secondary Mobile Applications file. Did we need to do anything with that, or did we take care of it somehow already? When I look at the Mobile Applications folder on my internal hard drive I see that it is 115GB. The Mobile Applications folder that is now on the external hard drive appears to be the same 58GB that was previously located in the "secondary" Mobile Applications file mentioned above.
(2) The Music/iTunes/ folder on my internal hard drive had a few folders that do not exist under the new external iTunes/iTunes Media structure. They include Books, a Downloads, and iTunesU. What do I need to do regarding those?
(3) The Music/iTunes/ folder on my internal hard drive had some folders that contained more files than ended up in the external hard drive versions of those folders located in the iTunes/iTunes Media. For example, the Home Videos (4.97GB compared to 191MB) and TV Shows (12.28GB compared to 740MB) and Voice Memos (45MB as compared to 9MB) contain more files on the internal hard drive than they do in the same folders on the external drive.
(4) I assume that I don't need to preserve the Previous iTunes Libraries or the Previous iTunes Libraries.zip files from the internal hard drive?
Thanks!