really - lots of questions.
I had a 147 with Connect Nav+ and got my GT this monday, with Connect Nav+ as well. Systems are exactly the same, except from voice recognition, which is improved.
So forget that we're living in the year 2004 and also forget nice features like CD-Text, Internet-Connection, TV/DVD, MP3...
Connect Nav+ comes with a holder for SIM cards, but it's better to put it in full size, just as it comes from your service provider.
You can use only one phone at a time. Decision which phone is "online" is easy: Always the last one that is switched on. So when you start the car, the phone in the car is online. When you stop the engine you have to switch off/on your mobile or call any number to reconnect it to the provider.
Targa Connect Service is no longer free of charge - at least here in Switzerland, and there isn't even a trial period included. We just have to pay for at least one year.
But - I have to say - the GT is really fun!
And - well, who cares, but - it's the most thirsty thing I've ever seen.
You have to stop the engine while standing at the station.