Hi Dickson,
Q1. Does Endpoint 12.1 include a Firewall by default?
--> Yes, In default package it contains Firewall. You can customize package as per business requirement.
Q2. Even though I disable the Firewall Policy in a Group, the Firewall Status is still enable. I try to run commands on computer to disable NTP on that client computer. From the Command Status, it cannot complete at all without any reason/indicator. The main task is to stop/disable the internal Firewall of Endpoint. How?
--> I would suggest deploy new package without NTP feature, reboot would required at clients to take effect.
Q3. Turn on Windows Firewall and Endpoint Firewall, any conflict?
--> Not recommended & it will degrade system performance as well.
Q4. If I want all client computer only to have antivirus feature without any firewall, can Endpoint create a client install package without Firewall installation?
--> Yes, as said earlier can create custom package.
How do I create and configure a custom Symantec Endpoint Protection installation package in version 12.1?
http://www.symantec.com/docs/TECH165801