Managing Vendor through corppass

1. Our system would be using corppass as authentication for our vendor user. We have a use case where our vendor user works for 2 different company and plays different roles in each company. For corppass authentication, is there a way to know if this user is logging in via different company? 

2. How do we add 3rd party Entities in our staging environment for testing? 

3. Is there cost involved for our vendor to set up corppass. What is the typical turn around time?