Hello,
1. PayPalAP: If you are using sandbox mode, please ensure that you are using sandbox credentials. If you are using live mode, please ensure you are using live credentials.
2. That is for tracking. If the tracking / shipping service you are using is not on the list, you can use some code to add more shipping companies for tracking: https://www.wcvendors.com/kb/adding-more-shipment-tracking-providers/