When I am in the car and not near wifi, can I talk and use text? I know I can’t use internet.
yes the $15 plan included unlimited Talk and Voice on Cell (3.0 has removed the old WiFi only plan)
Yes, as long as you have cellular coverage, you will be able to talk and text on the $15/mo plan even when you are away from WiFi.
Of course, while driving, local law enforcement might disagree with your choice to do so, especially texting!