When issuing command "Power Control" Shutdown or Restart to client which is in Automation - the task will be executed according to the Console - but client will stay in automation.
unknown at this time
For WinPE - If Shutdown is required you can use Run Script command with "shutdown -s -f -t 5" which will shutdown client machine.
For LinuxPE - you can use Run Script "shutdown -s now /y"
For the Restart it's recommended to use "Boot To" task with specifying the environment where clients needs to reboot (Production)