Milt,
Very good start. I have been building instruments for about a year now and have five completed. I second MikesFlightDeck books and his web sight. I use servos for gages that odn;t have to turn through a large range. In a standard airplane fuel, oil pressure, oil temp, and other guages fall into that category. For guages that require a full 360 degree rotation like an altimeter, directional gyro compass and so on use a small stepper. These systems do require some type of zero position sensor at start up. I am driving my guages with PIC microcontroller circuits. However, other options exist like Opencockpits cards and even the Arduino controller board. All of these require programjming ot both the pc level and at the instrument level to operate correctly.
You can find several pictures of my guages in the gallery section. I also made a mold for a 3 1/8 and 2 1/2 in guages so that I can cast bezels that all match.
Keep us posted about how you are solving these problems. Now you know why so many folks are building Boeing 737s with all glass cockpits.

Tripacer