Having to plug that in would still theoretically be a key.
Keyless is wireless. Not sure how you'd control the start, a separate switch, still having to use the steering column ?? If auto-start, how would you know when the engine is running? What if you wanted accessory to listen to the radio or on Run to pull diagnostic codes? What about the door locks that require keys?
Edit: Missed your last post, but now you are completely changing up your idea.. LOL
How in the heck would it be Windows?
I code microprocessors in AVR C under Windows, wouldn't make a bit of difference if I cross complied under Linux. An operating system would be complete overkill for a basic chip, but that's not even how it works. The compiler takes your higher level code (like in C for instance) and takes it down to assembly/machine code that's native to the processor, and the microprocessor works off the machine code written onto the EEPROM for instructions on what to do.