Breathe, you will get through this, although it doesn't seem like it right now. I remember putting myself in time out, in my room or like you driving around just to escape the tantrums. I have always referred to my now 7 yr old daughter as strong-willed.
I am sorry to hear you are struggling with these issues. I know you want to know if your son is OK and also figure out how to help him communicate and potty train, one of the best things you can do is schedule an appointment with his pediatrician to go over your concerns, your son's behaviors and responses.
It is difficult to give answers over a message board, but we can provide you with some resources to help out. You can also post specific questions to Dr. Benaroch, our expert on our Parenting Community for possible response.