EAP6.1 How to choose standalone vs managed domain HA needed

We have to install a production environment with the following architecture:
load balancer
--> NODE 1 HTTPD --> NODE 1 EAP 6.2

--> NODE 2 HTTPD --> NODE 2 EAP 6.2

• Load balancer redirects traffic to node1/2 httpd. Apache nodes must connect indiferently to any of the active Jboss nodes.

and we have the following requirements:

1- High availability.
- If one node goes down, other node serving all requests
- Not lose of service during deployments
2- Independent deployments in each node
3- Memory data replication. HTTP Session available in both nodes
4- External load balancers. Two HTTP servers in front the application server

We were thinking about implementing a managed domain, but some doubts came out to our mind:

1- Is it worth to use a cluster standalone mode in HA?

2- If we go for the managed domain thinking in terms of scalability
- Do we need a cluster as well for accomplishing REQUIREMENT 3&4?
- Do we have to create two groups in order to do independent deployments in both machines?
- What happens if the domain controller goes down? Is it possible to configure the other node to become the domain controller?

Thanks a lot!