d33my

I could be wrong but I don't think the Razbam Metro autopilot can do what you want it to do in this case. I have this a/c myself and can't get it to follow a GPS route either. The NAV ARM button seems solely to work with radio navigation (i.e. VORs etc). This is a known issue as the real Metroliner apparently has a very limited autopilot anyway. There is a large thread on these forums that have some people who (I think) have developed a more extensive autopilot for the Metroliner. It's a large thread though; hopefully someone more knowledgeable than me can provide you a link to their updates.

Yes a clean install of each is the way to go. One exception I can think of is if you have any A2A stuff -- you'll want to copy over any .bak files if you want to keep the current 'state' of your a/c. There are details on the A2A forums how to do this.

Don't have the Turbine Duke but I have the B60 and love it. There's something really fun about cruising around at FL230 in a GA plane. I've got the A2A Cherokee (as well as the 172 and P-51) and it's a blast too. I usually fly it IFR in bad conditions; it's a very stable plane. You'll have fun with all of them I'm sure.

I have this aircraft. guess you are pretty close to the engine where you're seated in the cockpit, but it definitely shouldn't be so loud as to make it unable to hear radio comms etc. From memory the user manual has a set of suggested sound levels you can try. If that doesn't work or you don't like it, play around with the engine sound slider until you find something that works for you.