There is no increased functionality with the $100 cable hookup from an application standpoint. However, for you to be comortable with my statement, you should answer two questions--1) How do you plan to get power to your device? and 2) How will you get HDMI connectivity? THose are the two features of the Pioneer kit, but you can accomplish both by other means. As I mentioned before, the biggest advantage of the Pioneer kit is if you have an MHL connector (the kit combines the two cables into one behind the dash).
On your other two questions:
1) Touch Screen: The Pioneer touch screen works fine for its own built in apps, like the Radio, settings, camera, etc. The ONLY time it works as a surrogate touch screen for the Android phone device is via the "AppRadio" icon. THis statement is partially clarified by the fact that the Pioneer Phone settings work within Pioneer's own touch system. By that I mean that when you connect your phone via BlueTooth, the Pioneer unit will automatically begin transferring your phone book to its own memory repository. Because Pioneer now has your data, the touch systems work accordingly (e.g., you can search your contacts, dial, etc.). So this phone functionality works independently from the AppRadio connection. The phone is all BlueTooth and internal touch screen. The other clarification is that there is a dedicated Pandora app, but I have been unable to consistently get that to work natively to Pioneer, and I don't know what I did that made it work the two times it worked. But when it worked, it was much better GUI than the Android, in that the Pioneer has more screen real estate and offers some options not available in my Android-only rendition, like time elapsed/remaining bar for each song, more detail on the song playing etc., and all the buttons work (thumbs up/down, etc.). So that was great. Because I can't get that to consistently work (and this is I'm sure due to my incompatibility issues), I still can use Pandora flawlessly, and do so often, by simply choosing everything from my phone. So because my phone is connected via HDMI, everything plays over the head unit, but the controls/touch screen for this is done native to the phone, not the built-in app in Pioneer. Also, because the media is going through the HDMI port, the digital processing is handled by the Pioneer head unit, not the Motorola phone, which I think is an improvement and the music sounds better.
The AppRadio button, when I select that, will automatically turn off the radio (if it was playing) and mirror everything on the Pioneer Screen that is showing on my Android phone. However, none of the Pioneer touch screen functionality is available. That setup is simply mirroring the Android screen via WebTop (WebTop is a functionality of either Android or Motorola or both). When I select the AppRadio button, that's how I play my Pandora, my local music, stream Netflix, or whatever else I have installed on my phone.
So the $100 cable does not add any functionality from a software/app perspective. THis connectivity kit is just that, it's a way to elegantly hook up your devices, supply power, etc. Before I got the connectivity kit I was getting power from a USB cable going into my cigarette lighter (cord dangles from the car mount). My hack of HDMI would get me into the back of the radio directly, and all works that way. With the connectivity kit, I drilled a hole into my dash, covered by a grommet, and have all the cords behind the dash. If I get an MHL device in the future, I can have just one cord coming out of the dash grommett instead of two
