Finally bought a Cummins!

Hi everyone, I have been a long time lurker on this site as I have been wanting a diesel for years. After looking at all the problems and things here and there with all the diesels I had my heart set on a Cummins, and I finally bought one. The truck is an 05 2500 QC/SB SLT in Mineral Grey I believe is the color.

Things done to it before I got it:
-stock (I think) 4 inch down pipe to a (not-stock) 5 inch straight pipe from trans cross member back
-drop in K&N air filter
-(as I removed the intake) It appears that they already removed the silencer ring
-I removed the baffle in the torque tube yesterday (4th day of owning it, lol)
-NEW 285/70-17 tires (How will that affect my odo and mileage reading?)

Here's what I want to do:
-tuner of some kind. I test drove one with a BullyDog GT window mount and liked it, and I've always liked Edge. Im not looking for HUGE gains and custom this or that tuning... I just want something with gauges and some different power levels. (why does everyone hate on Banks btw?)
-I want to install my Alpine headunit, but Crutchfield is telling me I need some sort of converter because I have the 7 speaker Infinity system... any idea what thats about or what I need?
-Stacks. Yay or Nay for DD?
-I love blacked out trucks, but being mineral grey how would it look if I blacked out everything I could (rims, headlights, tail lights, SLT chrome junk, color matched grill maybe)?

Any other tips tricks or stuff I should know about my new truck? Like I said, I've researched these things for a long time but you can never know enough. Any help would be great guys (and gals)

Thanks
Josh