Hi,
If you are planning to upgrade why don't you upgrade to the latest version i.e. SEP 12.1.
What's new in version 12.1
http://www.symantec.com/docs/HOWTO55189
What is new in Symantec Endpoint Protection 12.1?
http://www.symantec.com/docs/TECH163413
Go through following article also
https://www-secure.symantec.com/connect/articles/feature-differences-between-sep-11x-and-sep-121
To upgrade clients to SEP 12.1 or SEP 11, no need to uninstall SAV.
Push SEP package on SAV clients it will upgrade clients from SAV to SEP & After successful upgrade single reboot is required.
Also, on my server clients, is the recommendation to install only AV and anti-spyware and not the PTP and firewalls
--> From SEP 12.1 PTP features is fully supported with Server operating systems. About firewall it's your call, you want to go with Symantec firewall or third party firewall.
We do recommend to use all the three features to get full protection.