Paypal integration error in wordpress (CURL METHOD?)

Hi everybody,
I have a in wordpress classifieds theme (Classiera) with paypal integration for the subscriptions. I set up a sandbox in paypal and configured it in the theme options.
I get an error trying to buy a plan with paypal setted with sandbox:

Notice: A session had already been started - ignoring session_start() in /home/eagleman/public_html/ on line 2
Strict Standards: Non-static method WPCAds_PayPalAPI::StartExpressCheckout() should not be called statically in /home/eagleman/public_html/ on line 142
Notice: Undefined index: ACK in /home/eagleman/public_html/ on line 116

The Theme is Classiera (like a new version of Classify from Envato)
I think it has something to do with the paypal curl method, but i dont know what i need to ask to the hosting company eventually to update.
Anyone has a knowledge in this?