3 Node DAG with DR site

Hi team,

I have a primary site with 2 CAS (WNLB) and 2 MBX servers with DAG configured. I want to extend this to include a DR site with 1 CAS and 1 MBX server. FSW on Primary site is set to CAS server.

1. If the PRimary site goes down completely, is it correct that the DR DAG member will not come up since there's no majority?
2. related to Q1, what steps do i need to follow to get the DR DAG node up and running?
3. If I set up a secondary FSW on the DR Site CAS, can I get majority vote and get the DR DAG node up automatically?
4. What's DAC's role here?

Thank you.
Chris!