what is my paypal address – the email address I use for it?
Yes: The email address you log in to Paypal with
is this the usual procedure (& how does it work)- you give your paypal address out – if so what's to stop that person accessing it again?
It's not (they don't really need your address, but there's no harm giving it -it's just an email address
Do i have to authorise a request for payment? No
Do I have to put some money into the account first?
No – you'll have a bank account linked to paypal – or a credit card. Paypal will take the payment from this. It'll all be confirmed when you pay. You can add money into your paypal with your bank account first.