This is a tad off topic - but I was thinking of setting up a mastercard debit card just so I can pay for items instantly through paypal. Currently, paypal withdraws funds direct from my bank account but obviously this takes up to a week each time.

This may or may not sound stupid but I was wondering, with a debit account attached to my paypal - how will it work? Will paypal ask me how I want to pay for an item each time? If I pay using my debit, will I have to load it up first with enough funds to pay for the item before completing the paypal transaction? Will the conversion rates be any different?