[elav]

The key fob not working could be a number of things. When you press the buttons, do you see a red light come on? A double beep when you try to lock the car means that there is a fault. Seeing as you said your passenger side door doesn't lock - I would start there. Do you hear the passenger door try and lock? Could be a faulty latch mechanism in the passenger door.

As far as cheapest code reader, I would see if a local auto parts store will loan a reader to you. There are people on eBay that also rent Durametric cables for a reasonable amount. I'm sure there are a number of cheaper options, but people have also had good luck with the iCarSoft readers for Porsche.