It sounds like your son wants to dictate what happens in your home. And it sounds like he has control over his disrespectful and abusive behaviors because he can turn them on and off in different situations. But it's also important to understand that your son is going through a lot of emotional and physical growing pains at this age, and that when his emotions take control, his behaviors can quickly get out of hand.
Having said that, your son also is at the age where he wants to exercise his independence and do new things like get a driver's permit, go to school dances, stay out later and hang out with his friends. These are privileges, not rights, and you hold the key to whether he gets to enjoy them or not. So you can use these privileges as consequences to either reward your son when he uses positive behaviors (being respectful, following your instructions) or correct him when he uses negative behaviors (being disrespectful, ignoring your instructions). These activities are important to your son, so they can be a powerful motivation for him to change his behaviors.
Before you start using these consequences as part of your new approach to discipline, make sure your son knows what positive behaviors you expect from him and what negative behaviors you want him to reduce or eliminate. That way, he has a clear picture of what he needs to do and the consequences that will result from the behaviors he chooses to use. For example, you might have to clearly identify what respect looks and sounds like – behaviors like looking at you when talking, keeping his voice at an "inside" level, listening to you without interrupting and being able to calmly disagree with you when you give him an instruction or say "No" to a request (and then following the instruction).
Another key to success here is giving consequences to your son calmly and consistently. That means constantly being on the lookout for positive behaviors you can reward and reinforce and negative behaviors you can teach to and correct.
As for your dating situation, he knows he can't control who you see and he may be frustrated by that. Or, he may feel threatened by you having a relationship. You may have to be sensitive to this, at least for a while, by arranging dates at times when he has other plans or keep conversations with your friends private for now. There are plenty of families out there who balance similar situations.
You might also check out Boys Town's Common Sense Parenting book, which you can purchase at boystownpress.org. It has lots of great tips for dealing with teens.
