This is not true. PayPal is reversible. It doesn't matter how it is funded. Do not accept PayPal payment unless you trust the person not to reverse the transaction.
This. Regardless of funding method, it is reversible. CC is just easier to do since the CC company will say screw PP if PP declines to chargeback and the CC will chargeback anyways. But PP has its own chargeback mechanism and even if you pay with bank account or PP Funds, you can still chargeback if you dispute with PP and win.