It's too messy Tomas, I looked at splitting things out but there's no good way to do it without losing some relevant discussion. Hopefully it'll get back on track or Tesla will finally release the real FW v6.0......
Sorry Nigel, I feel I said enough on topic anyway, anyone else more inclined can Google further on the subject.
About the starting of the car from the phone this us an interesting dynamic because your key and the security in place is supposed to act as the barrier from theft. There was a pretty great description of the unlock and moving process behind this that was submitted to the NHTSA if I am not mistaken and a lot actually happens here.
Pulling just from memory the car does a check for the key when you go to unlock the doors. When you sit down it looks for the key again, and when you press the break it does one more check. If at any point it fails these checks it will lock down the car preventing it from moving. There was a far more technical description of this in the document sent and I don't know where it is off hand in order to reference.
Shifting this into your phone you would potentially attack this in one of two methods. Most phones have the ability to send other signals not just the cell frequencies being used to call someone or transmit data. Hypothecially they could emulate the key through the software in order to unlock the breaks and allow the car to drive. I don't know if the phone emits the right signal for this though and would likely limit it to a specific brand or brands of phones.
The second being through the 3g on the car using the exact same connection the app has by default. This would make it compatible with any phone that has the app and would not be brand or hardware or software specific (would just need to code in the extra menu option on the app which might be why it is IOS only right now). The interesting bit about doing it this way is not just allowing the car to drive away using the phone, but the way the connection is made, I could be on the other side of the planet and allow my car to be driven.
Hey Bob can I borrow your car? I heard you were across the country in LA for a conference.
Sure, hold on, I don't have a key to give you, but let me turn it on for you through my phone.
The implications are interesting, but I wonder if this breaches the requirements mandated by the NHTSA and if they will have to submit a waiver or something?