Regarding-1 : how we can get the CPU status of each policy server?
ELB cannot monitor the CPU of a backend server. ELB can monitor latency's based on Responses and take actions. It seems like ELB pretty much does Round Robin only for TCP listeners on Classic LB. You'll need an external tool to monitor backend servers.
Amazon provides something called 'CloudWatch' which can monitor all the components E2E.
Elastic Load Balancing Latency Troubleshooting
https://forums.aws.amazon.com/thread.jspa?threadID=58796
CloudWatch Metrics for Your Classic Load Balancer - Elastic Load Balancing
Elastic Load Balancing Capacity Troubleshooting
How Elastic Load Balancing Works - Elastic Load Balancing
Regarding-2 : when I was running webagent from systemctl LLAWP process failed to start due to siteminder load module in httpd.conf file.
CA SSO WebAgent LoadModule in httpd.conf is correct. What was the error you received in apache error logs? I would recommend you spin a different discussion for this. Rather than adding too many discussions in one thread here.
Regarding-3 : do we have any handy on auto start-up script for webagent process.
Since CA SSO WebAgent LoadModule is added in httpd.conf, when Apache starts, during that time LLAWP would also start. In reality you need to configure AutoStart for the WebServer. The WebAgent is configured with WebServer.
Regards
Hubert