I made a flight plan (using the one inside FS2K2), for KMCO to KLAX, using jet airways. Cruising altitude is 35,000. I'm flying using the autopilot (in a 777), and making turns this way and that as Jacksonville Center is calling them out (right now, anyways). I'm doing this using the Heading Hold (HDG) function on the autopilot. My question is this: How exactly does one use the "NAV Hold" function? I'm noticing that when I change the CRS number, the white needle running the diameter of the EICAS display changes according to whatever CRS heading I choose. What exactly is this for (how does this all fit together with NAV1/NAV2), and is there a guide somewhere that explains this? I have completely no idea how to use those functions, and would greatly appreciate any of your help.
Also, I've set the Mach hold to .84, and my primary flight display is indicating 300. Is this the IAS, and what IAS translates into .84 mach?