EDGE Load Balancing

Hi,

We are in a escenario with Exchange 2013 SP1:

3 Mailbox-CAS Servers (Server1, Server2, Server3)

2 Edge Servers (EdgeServer1, Edgeserver2)

The Three CAS Servers are in the same Active Directory Site. We have a Hardware Load Balancer for Server1, Server2 and Server3 and another Load Balancer for EdgeServer1 and EdgServer2.

The goal is that if one EdgeServer fails the Mail Flow don't stop.

Our questions are:

To send mail:

We have to do two EdgeSubscriptions between for example Server1-EdgeServer1 and Server1-EdgeServer2?

To Receive:

The Idea is that the MX register points to Hardware Load Balancer IP. Is this OK?

Thanks in advance