If you don't mind, I have made so many tags changes in order to get the DX50 right. I keep my filename to 30 chars max, that includes the track number at the beginning and the balance of the title. I religiously remove any quotes and commas in the title or for that matter if you can any punctuations of any kinds, it used to choke on that. The main tag items you need are title, author, album, track number and genre. You do not need anything else. Naming in this is everything, case will matter. Its, ITs and ITS are very different for the tag library, it will bunch things together according to case so name you stuff consistently and carefully, it'll aggregate your songs together at the right place. If you have a PC, use the mp3tag app, it allows making all those changes in a clip.
One more thing: art works - Either deposit a file with the .jpg extension (name does not seem to matter). It will use it if you haven't embedded the art work in your file tag. If you want to use a specific one for a song then embed it in the song tag info and it will use it instead. Both can reside in the same directory and it will pick it up first in the tag, second in the folder. Do not keep multiple jpg files in your directory, only one is sufficient the other ones will be ignored anyway.
Hope this helps.