The 3 days/3 plays thing only applies to a Zune to Zune wi-fi transfer. Hopefully the retailer whom you're buying from had this information.
Are unlicensed MP3 files allowed to be copied to Zune? Or do the MP3 files which were copied from PC to Zune disappear after three days or three plays? I mean, does the copy-protection work during synchronizing as well as during wi-fi transfer? I need a very urgent reply since I'll be buying in a few minutes. Thanks.