Back to OP, I recall Paypal places a limit on the amount of transactions processed via credit cards. (Maybe lifted recently? I am not sure). Depending on how much payroll you have to handle, you better make sure you won't exceed the limit (if there's any).

Both personal and business/premier Paypal accounts can be funded via credit cards. Like others had pointed out, you don't have to use the bank account. The difference is on the recipients' end. If it's the creditcard funded payment, the recipients have to pay a fee. I haven't use my Paypal accounts for a while so I am not sure what's the current fee structure. However, if your employees' Paypal accounts are the personal type, I am sure they won't be happy to see the fee deducted by Paypal from their accounts. It wasn't an issue since you used to send bank-account-funded payment and there's no extra fee involved. If you are going to switch to the credit card-funded Paypal payment, well you have to factor in the fees now.

You better research more and see what fees you and your employees will have to pay to go this Paypal credit card route.