Hello,
I just upgraded from my DEH-9800BT to the AVIC-D3, well worth it, the touch screen is soo nice!
I would not waste money paying someone to do it, if your comfortable with the changing radios you did before, you'll be fine.
To answer your questions:
-- install is pretty straight forward. The only thing that threw me for a loop is that you have to access 3 wires in the harness in the fuse area ofthe dash of the car. A little tedious, but not horrible. (not worth $300) :-) They wires are the parking break sensor wire, car speed wire and...forget the last one. The unit needs the speed for hte Nav and the parking break they have set up so you can't fool with to much nav while driving and watch movies without hte break engaged. there are some ways around this, but not worth the Nav possibly not being as accurate.
- the steering wheel controls you need to buy a special unit to interface with your new radio: like this:
http://www.crutchfield.com/S-6qlBYc8...ols&i=127SWIPS
as far as i know that is the only way to do this.
- i had blue tooth with my older unit, didn't buy with this one, but was easy to run the mic accross the dash and brought it up hte left front pillar of hte windshield and put the mic on my visor. My data phone no longer works with it, so decided against it this time.
I have always used crutchfield and they are superb in helping with the install, free shipping and no tax! They were able to tell me which wires to splice into the for hte nav funtions, for example look at the 12 pin plug for the white wire with blue stripe. priceless in my opinion, there are alot of wires :-)
I did sirius, amp, custom sub in the back, and replaced all speakers with Infiniti's if you need any more help hit me up. HOpe this helps ya.
Chris