Not sure of your mechanical abilities, but the work you said they are doing is well within the scope of a basic DIY'er. Your looking at maybe $400 in parts and a couple hours of labor. As far as the window, look on youtube for video. A pretty simple procedure. Get a good quality regulator, especially since it is driver door that gets used all the time. Pelican has all the parts you need. I have nothing on the EPROM msg.