That is why now I just support USA and Canada. PayPal does not care as long as IPs for US accounts are located in North America. Yes, if they see someone from Poland for example is trying to login into US PayPal account they will ask additional security questions to make sure account was not hacked. I am also considering creating an applet to tunnel SSL connection to Paypal through users browsers. This way there will be no problem with IP addresses as they will come from the users computers
There are no losses to the site as the risk is transferred to the users themselves. But users need to make sure that transactions are small and they don't keep large amounts in their Paypal accounts that they set up for trading
Using a bot to log into other people's paypal accounts will cause problems. You will need more than just the username and password. If the account has not been used recently, or is logged in from a significantly different IP address, paypal will let you log in, but when you try to send money, you will get asked the security questions.
You might be able to get away with making a bunch of throwaway (unverified) accounts. If you receive only a small amount of money into each (less than $500) you could get away with it. You could then pay the money out after waiting 60-90 days to make sure there's no chargebacks. This will be a lot of work, and some of the accounts will get closed due to suspicious payments, so you'll have to factor these losses into your fee schedule. You'll also have to be careful of getting your IP addresses banned.