Yes: you and his father need to enter into family counseling immediately, if this marriage has an even small chance of surviving. Your step son's hair color has nothing to do with his behavior, and the belief that red heads have a temper is merely a myth. But behavior problems do exist and are sorely in need of attention and resolution, promptly. If you look at his misbehaving as a symptom of family dysfunction, which can also include his relationship with his own mother, you will find it easier to avoid blaming or even disliking him.
You and his father need to come to terms and agreement about disciplining and each of you needs to back up the other one. Chances are he is not accepting you as a mother subsitute (yet) and resents your intrusion, as he perceives it, into his family. There could be many other issues, e.g., he might be angry with his own mother, feel abandoned by her, takes it out on you, etc. He may be testing the waters of the new relationship,and more. You have bitten off a great chunk here, by marrying this man while he still has full custody of young children. If you don't do something about it now, (good family counseling), i would easily predict that your marriage will fail, after a prolonged period of misery and chaos for everyone. Really, you shouldn't have married until the children were older and stabilized, but too late for that now. Good luck, good wishes, get to work on the counseling and I hope this will not only save things, but indeed, improve them.