The Cluster ActiveGate requires:
Even more important. It's required as endpoint to receive the data from the public locations.
Agentless Real User Monitoring, mobile-app monitoring, and synthetic monitors all use the same endpoint to transmit monitoring data to Dynatrace.
You do not need to, but it's advisable to deploy behind a load balancer, especially when you deploying more than one CAG's. See the link ratislav shared.