Well, first of all, you have zero protection if you pay for a service with paypal - it's a "virtual good" and there is no buyer protection for that.
You can transfer funds instantly if you pay by credit card and I would strongly recommend that you do so - your credit card CAN do a chargeback if the service isn't performed.
The seller can transfer funds from Paypal as soon as the funds are both clear and available. If the seller is a new seller on ebay, the funds may be held for 3 weeks but that should not affect their delivery of service to you. They can download the money to their bank account in 3-4 days.
