Dynamics CRM 2013 IFD - Exposing server to public

Hi All,

Need your help to correct my understanding in implementing IFD. 

1. Do we need to expose both MS CRM and ADFS servers to internet? That means, do we need to have public IPs for both CRM and ADFS servers?
2. If there are multiple front end CRM servers, do we need to expose all MS CRM servers to internet? Do we need to buy wild card certificates for all?