P.M.
You're describing a normal-enough situation for teens – school doesn't seem relevant to quite a few kids at this age (truthfully, for many kids who are not academically oriented, it's NOT especially relevant, and a trade school would be a better option). Sleeping late, staying up late, hanging out with friends who "understand" them, challenging authority. All of it is "normal."
But this doesn't mean it's optimal, by a long shot. And it would be hard to take. If I were doing the cooking, laundry, or other motherly tasks for an unappreciative step-son, I'd be inclined to offer him a deal. Either he starts considering my reasonable needs, or I stop cooking and cleaning for him.
What it would mean to do his share could evolve as needed, and wouldn't necessarily have to include Dad's cooperation. Ideas could include behaving respectfully, following basic household rules, sharing chores, getting a job, saving toward his future independence, volunteering some of his time in the community… there are lots of good, healthy options. I'd want him to take responsibilty for helping to choose what he agrees to do.
And I would NOT hold my breath expecting that he "must" change. He has reason to believe he can get away with "whatever." If you put your foot down, be prepared for flack from your husband and possible even worse behavior from your SS. Meanwhile, get yourself a good book on co-dependence. (CO-DEPENDENT NO MORE by Melody Beattie is a good one.)
This boy can hardly be faulted for having bad habits, since it sounds as though his role-modeling has been lax, to say the least. As sad as it may be for a sensitive soul who wants to be responsive to the needs of husband and family, your SS may simply need natural consequences to help him realize that other people have legitimate needs. So, if you try to tough-love it, work on keeping your communication about what YOU NEED, not what others are doing wrong. Much more effective (and less whiney).
Here are some excellent resources to get you started:
There are a some helpful videos at http://www.naomialdort.com/lectures.html I have been reading and applying Naomi Aldort's advice for several years working with my grandson and young children in my religious community, and we have all been better for it.
Here's a fine video on communicating with children in a way that respectfully connects with their needs, and results in a much greater likelihood that they will (eventually) be able to hear your needs: http://www.youtube.com/watch?v=IQO7h9MNCqI That one's for younger kids, but the ideas adapt to any age. Look up other links to Non-Violent Communication for some powerful techniques for getting to the heart of other situations, as well. It's all about recognizing, respecting, and responding to the legitimate needs of all involved.
Good luck, Kerry. Teen years can be challenging enough with your own kids. My second husband, and my daughter, had to endure a great deal of pain when we married. My daughter was entering adolescence, and there were many adjustments to be made all around. (But it eventually worked well for us all, and my daughter grew into a mature, happy, responsible mother and loving step-daughter.)