where as i am against texting and driving, i will always say be very careful when doing these sorts of things.
#1 the words may not be read out entirely as you want it, and then require you to check to see what it said.
#2 it is still dangerous and most messages are best left unread until you have come to a complete stop
#3 these apps may not yet work well with JB but you are more than welcome to try
jb has a Text-to-speech output
Settings
Language & input
speech
Text-to-speech output
i have never tred this but you are more than welcome to try.
i suggest testing this while in your home, just to make sure it works.
again i am not trying to tell you how to do something, just looking out for your safety, it only takes one time for a phone to become an issue when driving, and that one time may not end up so well.
just be extremely careful.