Dear Val, the links are indeed helpful. This is exactly what I was looking, many thanks.
I have one query related to this - which I could not see, that is do I need to install policy after each upgrade? And if yes than both cluster member or the one which is upgraded/not upgraded select for policy push? I am not sure if HotFix upgrade requires policy install step.
Earlier when I did policy install step it was when OS was upgraded R77 to 81. I have change the version name from r77 to r81 in Gateway Cluster Properties-->General Properties-->Platform--->Version and then push the policy.
I followed these steps while upgrading from R77.30 to R81 take 392:
Start with Passive Firewall(ideally)
Install latest/recommended Deployment Agent(DA) if installation is not automatically enabled on the firewalls
Upload/Copy of IOS Image on the concerned firewall
Verify IOS Image - Check_Point_R81_T392
After successful verification - Upgrade FW with IOS image
Upload Hot Fix - Check_Point_R81_JUMBO_HF_MAIN_Bundle_T77
Verify uploaded Hot Fix_Bundle_T77
After successful verification, Install Hot Fix
Change Name to R81 on MDS
Policy Push for version R81 after First Firewall IOS & HF upgrade
Revert to Clish Mode in the both Firewalls CLI
Repeat same steps for Active Firewalls
Policy Push for version R81 after First Firewall IOS & HF upgrade
Make sure Primary Firewall is now active