Hi ka-icontracts,
To answer your first question, you enter your PayPal account in Contact -> PayPal Settings -> PayPal Account.
Regarding permissions, it should only give that error if you are not an administrator. Could you double check your account in Role -> All Users -> (find your account) -> Role column.
The error you posted is very strange, I have have not seen it before. Are you using WordPress multisite?
What do you mean by two level pricing?
Thanks,
Scott