What about power to an alarm? What is the output voltage of that power supply?

You really don’t want to do this. Read up on how ftp uses random ports and is not really secure and you will quickly change your mind. A good alternative is SFTP, part of SSH. It uses the same port and is much more secure.

Are you looking for software that can run on an installed OS to emulate the PXE bootloader that is normally in the NIC firmware? If so, I’m not sure one exists. Even the name Preboot Execution Environment implies this happens before an OS is running.