I don't know if I'm really contributing much to this conversation, however...
In regards to having the opening of the doorhandle unlock all the doors simultaneously (I assume this also includes the hatch), I think there might be a possibly simpler way to go about it.
I'm not a big computer/electrical/wiring guru, however I am aware, as some of you may already be, that if you walk around to the front passenger door and unlock the car manually with your key, it electrically unlocks all the doors, including the hatch.
Now, it would be possible to replicate this mechanism which responds to the turning of the external front passenger keyhole and install it in each door in such a way that it therefore responded to the pulling of the interior handles and unlocked all the doors of the vehicle?
Despite how much I love my car, they really weren't thinking that much about convenience when it came to the locks...