Welcome to the forums!
Sounds like fun, congrats on the new ride. I don't know much about cruise control installations, but I do know that my factory-fitted one sees very little use - it's a real fuel waster.
You set the thing for a certain speed and it maintains that. The biggest waste comes when you reach a hill - where a person would normally gently apply accelerator to maintain or "slowly lose speed to pick it up again over the other side", the CC just plants it in order to maintain speed.
It's definitely not something I intend to *ever* use while towing, too.
As for noise reduction, you can put panels in the door and spray some stuff under the cabin to help with that, but a diesel is a diesel. Mine is a major change from the car I traded in - an excellently maintained Commodore that was so quiet, you couldn't tell the engine was running at 80km/h and if I was in the forest idling the motor over so I could charge a battery up, you really had trouble telling. It's something to get used to, for me.
Extra sting - there are all sorts of performance mods you can do, the most common seem to be:
Larger exhaust - might be more valuable to your 3.0L engine than it would for the 2.5L. Several people with this mod believe it has value so I'd lean in the "yup" direction.
Chips - replacing the chip that controls the fuel injection etc can help with not only power increase but improving fuel economy as well.
Diesel Gas - I only know that this mod gives you more power. I think it's expensive and not sure if I'd ever bother with it myself.
I'm so happy with the performance of mine at the moment (except maybe its fuel economy) that I'm unlikely to do many of these. I'm leaning towards some ECU modifications, there's a thread nearby where we're discussing changing the injector duration because the cars perform better or worse at different altitudes, but that's as far as I think I'll ever go.
You could also look into things like lift kits, suspension upgrades and more. I might eventually get the rear suspension done, because we're looking at a fifth wheeler and they place about 400kg on the rear axle (my current van puts about 180kg down on the towball).
Anyway, welcome aboard, hope you enjoy the ride and the forums!