Aftermarket stereo with USB option for 2006 model

Hi everyone, I've been reading into this part of the forum for quite a while now, since I want to add USB functionality to my car. Although I've found lots of useful information, I also have quite some questions.

Inspired by the stealth install thread, I started looking at all the available options I have. In short, those are:

1. 2-din replacement of stock radio (with possibility of navigation)
2. single din radio in addition to stock radio
3. Parrot carkit with Bluetooth, USB and iPhone connection (MKi-9200)
4. Parrot Asteroid carkit/tablet

All of these options have their pros and cons. Specifically, option 1 is the most expensive and least attractive (looks wise). Option 2 is a very nice option due to its invisibility in the compartment below the stock radio. Option 3 is most likely the easiest to install, gives me Bluetooth call functionality as well, but is more expensive than a single din radio. Option 4 also looks interesting with not only Bluetooth and USB, but also apps like Spotify and Tune.in available on the 'tablet'. However, that is well beyond the price point of #2 and 3.

Price point set aside, I'm wondering what I have to do to wiring in each of the situations. As far as I've found, both radio options would need a custom harness to accomodate the different plugs? I'm not willing to adjust anything at all about the standard wiring. I am, however, willing to use a wiring harness (if that's possible) that I can buy on Amazon or such and plug it in between the default wiring and the radio, because that can simply be removed. So my rule is: no cutting/stripping of stock cables.

From the Parrot I know that I only have to use a wiring harness that fits in between the wires going in to the stock radio. However, the Parrot has an 'old' iPhone connection for connectivity, so even though it also has USB (not for iPhone, only USB sticks) and SD cards, it's not my favorite.

Therefore my preference goes to either a regular radio (without having Bluetooth) or the Parrot Asteroid.

Finally, I don't mind losing the steering wheel controls, as long it's only the audio part. A/C would need to remain available.

What would be my best option and especially: can anyone comment on what kind of wiring I would need to buy in order to connect a regular radio?