Thanks for sharing that info.

A few answers that you may find helpful....

1. Their accounting is actually correct, but only from their perspective. There's a reason for it, but it seems backwards from a user perspective though and confused me at first.

Their maths goes like this: (Amount USD - xCoins fee) x % profit margin = Your profit (lenders fee)
After that they add the PayPal fees to get the total USD amount that is sent to your PayPal account.

2. I don't think that they vet the sellers. There's no real need other then standard KYC (BTC transfers are irreversible).

3. That's unusual. Check your BTC balance to see if your account was debited. The buyer may have cancelled the transaction.