If you must link PayPal to a bank account, link it to a secondary one, not your main one. I understand they can 'dip in' to your bank account. Too bad for you if money is tight when they do.
From memory: PayPal had a big struggle against fraudsters. It got quite used to closing merchant's accounts and keeping their money. It's like a bank, but less regulated; they've got your money and it's up to you to prove your sales are legitimate, for you to get it back.