I have a Nokia Lumia 800, running WP7.5. I have similar problems, but have done the following to make the best of the situation:
1. On the MKi9100 - change voice control to "phone" instead of the parrot. That way I can use the phone's voice activation and create text messages hands free. The voice recognition on the Lumia 800 is great.
2. On the Phone - in settings/speech, set "read aloud incoming text messages" to "off". It's a shame we can't use that feature effectively with the MKi9100, but by turning it off, at least incoming text messages don't interrupt the car stereo and ask "who do you want to call?".