I'm going to to an extensive FAQ on this, and hope it will be included in the NSXFAQ on this site.
Unfortunately, I'm on business in Europe this week, and can't find the time to start authoring the text. One thing I regret is not taking photographs during the conversion process. I will likely take photos of the "old" components once they are removed, since anyone who is going to do this already knows what they look like installed. I'll also have photos of each component installed in the car.
Short answers for those who want to know:
1. The microphone and keypad thing on the console is simply an insert in the coin tray. A few holes are cut in the coin tray to accomodate it (I believe the phone is a dealer installed option), so you have to deal with these accordingly. I mounted the handset cradle here.
2. The factory microphone is not reused. I mounted the Nokia microphone on the dash near the TCS switch.
3. The factory center speaker is reused and sounds fantastic.
4. The radio mute function is preserved.
5. The factory antenna wiring CAN be reused, but it is difficult to get through the firewall. Also, the antenna must be replaced, as an antenna for digital service frequencies is different than for analog service. In my case, with AT&T Wireless, I used a flat-glass mount TDMA 800/1900 & AMPS antenna mounted on the rear glass in the inside of the vehicle (no external antenna visible).
6. The Nokia "handset" (not to be confused with the phone/cradle itself) is mounted in the center console where the old Motorola/NSX handset was located.
My initial intent was to reuse as much wiring in the NSX as possible, although soon into the project I realized that this was not necessary. You'll all see why when I do the photos and FAQ.
EDR