Is it Possible to Access Contact Roles and Attachments from Potentials API?

Is it Possible to Access Contact Roles and Attachments from Potentials API?

I am using the Potentials API for the first time and need access to all of the Contacts (Contact Roles) for a Potential.  Is there a way to get all of those Contacts?

I would also like to use the API to access/download the attachments for Potentials, Contacts and Accounts.  Is that possible?