Hi James, let's see if I can answer all you questions.
1. Thermocouples require two reference points, cold and hot. The cold joint is a temperature compensation diode at the back of the instrument or at the EDC (CGR and MVP installations). The hot point is where the TC wires meet at the probe tip. We specifically designed un-grounded probes to increase reliably. We isolate the TC wire from the actual probe as the two different metals (alumel and chromel), as well as the actual probe and solder all expand and contract at different rates, eventually fatiguing the joint. That is typically why grounded probes fail at a much faster rate. The TC wire is actually soldered to the probe tip.
2. The CGR-30P always includes RPM, EGT and CHT (bar graph analyzer). You select 5 primary and 5 non-primary functions. Primary functions are those with limits/redlines that will replace existing instrumentation. Worth noting, if you elect to monitor fuel level, each tank occupies one primary position.
3. All of the probes and transducers connect to the EDC (engine data converter). The CGR-30P is wired to the EDC via two RS422 wires. For added safety, fuel and oil probes/transducers are installed on the engine side of the firewall and sensors such as vacuum and manifold pressure are installed on the cockpit side of the firewall. You can keep the Insight gauge, but you would need to install many redundant probes. For example, EGT and CHT. The Insight probe cannot supply signals to both their system and ours. If you were to remove the Insight instrument, our system can interface with the existing probes, saving you labor.
4. The CGR-30P easily interfaces with most panel mounted GPS units to provide MPG, distance to empty, fuel remaining at destination, time to empty, estimated total remaining, etc.
5.If you wanted to monitor amps, we can supply you with a 100amp shunt, or you can use your existing shunt. We would need to know how many amps are required for a 50mV drop across the shunt so the CGR-30P can be calibrated correctly.
6. If you wanted to monitor vacuum, we would include our PT-05DIFF transducer to do so. The transducer includes two hoses. One to be connected to the gyro pressure line and the other to overboard pressure.
One final consideration, we are offering a 30P and 30C combo package with a very attractive introductory rebate. Up to $1000.00 off. Basically, we're adding the 30C for an additional $400.00, which is incredible as the 30C can replace up to 16 primary instruments. 8 are included in the purchase price.
I hope this helps.