- The second one is correct putting the corresponding ProxyPass configuration for /alfresco and /share in Apache frontend with their corresponding hosts. The access from the frontend allows to use services REST/CMIS from clients, use mobile application or access to Admin console. I would say that share.host and alfresco.host are correct.
- Relating the first figure, both share.host should be the IP of the Load Balancer A. I missed a load balancer C (or an Apache with mod_balancer) between Share nodes and Alfresco repos (if you plan to deploy share.war and alfresco.war in different machines). In the link (scheme) that you provided, share.war and alfresco.war are usually deployed in the same tomcat container and host.
- If you are using a cluster, you are an Enterprise customer. Please validate the architecture in the support portal.