I'm with Tazz, it sounds like one big phishing expedition where they are trying to get email addresses and as much personal information as they can for a number of reasons the least worrisome is spam but the potential for at least partial id theft is also there.

Make them go through the "pay now" tab and make sure you use a trackable postage method, even if it doesn't insure the goods at least you can prove to Paypal that you sent it!