I would recommend never using PayPal or considering an offer at a low rate. It is a drag, but you should either use localbitcoins or research exchanges in your country then fund your account with a USPS money order. Then, after executing a buy, withdraw your bitcoin right away. If you do not have total control of your private keys then you do not own any bitcoin. An exchange could close anytime and leave you Satoshi-less.
Why wouldn't you use paypal to buy ? I understand why wouldn't you sell, but I don't see the harm in buying.
No, it is because trading bitcoin is against their TOS. I don't trust them to do the right thing in a dispute since I would be operating outside of their rules.