Jemplode will do the second thing, which is to write ID3v2 tags back into the files as you download them off of the player.

As far as the first thing, playlists, that's a different animal. If you download things via Jemplode you can have it create a folder structure that matches your playlist structure. Which might be fine for some people.

A case where it wouldn't be fine is if you have the same song (or album) in multiple playlists. Then, if you download each playlist off of jemplode, you might download the song more than once.

Relevant FAQ entries are here:
Can I copy MP3 files back onto my PC from the player?
Is there anything I should keep in mind when I grab files from the player?
Can I back up the player's playlists and music files?
What is the best way to organize and listen to my music?
How can I keep my PC and my car player in perfect synch?