as for texting with the touch screen, I recommend this.
http://tiltsite.com/2008/05/htc-diam...and-available/
As for the rest of your discussion, it should ultimately be up to the student. If hey understand the subject they have nothing to loose. As long as they do not distract the other students they should be able to text, if they need to make a call then go outside or out in the hall. It makes sense to say teachers shouldnt be able to text during class because they are teaching, if a student is giving a presentation they shoudnt either.
In the real world, you rarely see a meeting where you are required to power off your phone. I would be pissed if I were told I need to put my phone away for whatever reason. Anyway, the entire purpose of school is to prepare the next generation for their jobs in the real world by teaching them these things, not telling them to pretend their phone doesnt exist for an hour and 15.
When I am giving a presentation I don't feel that people are being rude to me when they pull out their phones. They don't do it because they don't care what I have to say, they know and I know there are more important things in the world. If people care what you have to say and are genuinely interested, they will be respectful and limit their texting to a minimum.