The federal government is responsible for collecting and administering Social Security. State governments do not collect Social Security taxes or administer the program.

The state provides security in any government, so this question is superfluous.

The National Security Council is under the executive branch of government.

You have to employed by the private security company who has the security contract with the government. Most of the times some government building do not want to hire armed security people. Government buildings want armed security guards to be qualified as SPO. you will be working as an Armed Security guard but your title will be SPO (Special Police Officer).

Not usually but possible. Normally a security guard works for a private company and a law officer works for the government. A government agency may hire the private company to provide security guards.