I am replacing an AVIC D3 with the NEX 4100 tonight.  I have an iPhone 6 plus.  Do i need the CDIH202?  If so, what does it do?

My intentions were to mimic my screen for use of Siri, texting, and apps, as well as music etc. 

I have a lightning cable, RCAs, etc., this is not my first install (20+ years of it).

Just not sure what the whole HDMI/CD!H202 does? 

What will/will not work without it? 

With just the lightning cable to usb1, you get CarPlay (with its limited selection of apps including maps, music, siri, and texting (by voice)). My understanding is with AV adapter, you essentially mirror the phone onto the nex, but I have not tried nor seen that. I'm curious if you still get CarPlay with that since, if so, then cost is the only reason not to do it.

If you plan to just use CarPlay, then all you need is a lightning cable. If you plan to use app radio you will need an apple hdmi adapter, hdmi cable and lightning cable.

Do not buy the cd-ih202, it is just a high priced Hdmi cable, and a cord not used on the 4000/4100. Just get a quality Hdmi cable, lightning cable and apple a/v adapter(only if you plan on using app radio).

But AppRadio is broken for iOS 8 right? That's what Crutchfield has told me

But AppRadio is broken for iOS 8 right? That's what Crutchfield has told me

It works for me, iPhone 6 IOS 8.3. Athough, i hardly ever use it. I do not use carplay either.