Assuming the question relates to messages to persons other than themselves, the answer is most definitely NO! The procurement of such information would require an order from the court designating "need to know".
Yes, if you believe that your text carrier won't or doesn't have the ability to read your texts (in or out going) either at their own discretion, or at the discretion of law enforcement, then you are...
Yes you can, as long as your carrier have this package when you bought your cell phone. Now a days all the company of different cell phone have this free minute and 1000 of free texting.