Okay, checking back in now that I have a replacement phone. Here's what I have learned:
Unknown Artist : there were two factors here. It wasn't the order of the tags or iso vs utf as I had thought, it was a)the fact windows phone doesn't like 'illegal characters' in tags, so AC/DC shows up as 'Unknown Artist' and has to be tagged as 'AC-DC' or something similar, and b)the other 'unknown artist' files were the ones with all the extra garbage 'priv' tags. Once the tags are cleaned up all is fine.
Unknown Year : Here's the REALLY strange one. If you copy your files over usb cable, it uses media transfer, not mass storage, and the year WILL NOT appear. Ever. Yet if I copy any of the files back to my pc, the tags aren't modified in any way and are 100% intact. Now, are you ready for this? If you remove the sd card from the phone and connect it to your pc directly as an external drive, and THEN copy the files over, reinsert into phone, voila, you get the year.
Unknown Artist : there were two factors here. It wasn't the order of the tags or iso vs utf as I had thought, it was a)the fact windows phone doesn't like 'illegal characters' in tags, so AC/DC shows up as 'Unknown Artist' and has to be tagged as 'AC-DC' or something similar, and b)the other 'unknown artist' files were the ones with all the extra garbage 'priv' tags. Once the tags are cleaned up all is fine.
Unknown Year : Here's the REALLY strange one. If you copy your files over usb cable, it uses media transfer, not mass storage, and the year WILL NOT appear. Ever. Yet if I copy any of the files back to my pc, the tags aren't modified in any way and are 100% intact. Now, are you ready for this? If you remove the sd card from the phone and connect it to your pc directly as an external drive, and THEN copy the files over, reinsert into phone, voila, you get the year.