PSEN is Programming SErial Enable!
That is not the meaning of PSEN it means Program Store ENable, it is the !RD signal for external code ROM.

You pull it down (from NoConnect) and if it is in this state, after reset the chip goes into program download mode over serial interface, otherwise it starts running the program from program memory. Since the chip needs to recognise the state of the pin (programming enabled/disabled) it obviously MUST be an input!
1) It is an OUTput that has been called to double duty.
2) When you get a fresh from factory chip you do not need to muck with these pins, it will go into program mode regardless, and, if you install NoTouch or "the backdoor" in that process, you NEVER have to muck with the pins.

Erik