cyclonus99

Crossposted this in the 2nd-gen RX forum. Figured it would get more traffic here.

Hi all:

I just got a 2009 RX350 without nav, non-ML audio system. I am looking to install the Pioneer Avic X930BT as well as a backup camera. Here are the components I'm looking at getting:

Headunit:
Pioneer Avic-X930BT

Ipod Controls:
Pioneer CDIU-203V Ipod audio/video cable.

Steering Wheel Controls:
PAC SWI-PS

Backup Camera:
Boyo vtl425 ultra slim

Trim/Harness
I'm undecided on this. There are 2 options:
1) Beatsonic SLA-82A if I want to do plug and play, retain use of the factory amp.
2) JDM Toyota Harrier double din trim piece + Metra 70-8113 Toyota harness if I want to do factory amp bypass and use the aftermarket HU's internal amp.

Questions:
2) Does anyone have any opinion about the two choices of using the factory amp vs doing an amp bypass? I have heard complaints about noise/hissing using the factory amp with an aftermarket head unit. I could save a good bit of money doing the amp bypass myself, and probably better audio quality.
3) If do an amp bypass, why would I need a separate metra harness? I have read on the forums that this harness is required.
4) Does anyone have a link to the wiring diagram for the the amp/speakers for this car?
5) Is the ohm value on the factory speakers 4 ohms, or 2?
6) Am I missing anything? Any other components necessary?

Thanks in advance!