Hi Dave,
The red display on my unit is very red and I don't think it goes well with the amber dashboard so I prefer blue.
Yes the Alpine does drive the sub volume but not quite as bassy on all the tracks but most are fine, the sound is good.
No I did not get the harness for the steering wheel controls, the dealer I got the gear from said he had put them into a few other vehicles and had not been without issues, also i don't have the wheel with the controls on but was looking to change it but now I won't bother.
If you don't want to use the Nissan amp then Alpine do a head unit power pack KTP-445 (4x100w max).
Any other questions feel free to ask.
Hope that helps.