>>1,4,6
What chip is meant to go on this PCB? ASIC? MCU? CPLD? If the "Fn layer" is the only part not implemented, what is the rest implemented in? If this thing needs to be programmed and it is a common microcontroller, you'll need to program more than just the "Fn layer", or at least have access to the existing code that implements the rest of the controller. MCUs of the sorts that go in simple devices are wiped and reburnt as a whole to modify code, unless it has some BASIC or Forth
(or Scheme) interpreter running EEPROM tokens.