We are deploying all new domain controllers (DC). Is there anything that needs to be loaded on each DC to support QAS?
Domain Controllers themselves do not require any services or applications to support QAS clients. Prerequisites for QAS in a domain include a schema extension, and with version 4.0, a configuration container in Active Directory (AD). You may also consider Group Policy requirements for your clients.
None of the above is DC specific. Rather, they are domain-specific.