SSlmclarengt, I didn't read what you wrote but basicly how PayPal works is along the guidelines of, if there is proof the recieved the thing they paid for, you can't charge back. Otherwise, you can charge back anything.
Sending something to them via mail and having them "sign for it" and providing a tracking number is the best and most safe way to do things via paypal. If you send it unlike this, such as an "e-Good", there is no proof that they ever got this "e-Good" so they chargeback. PayPal saids, hey I don't know he wants his moneyz back.. Give him it.