Start slowly with one thing. In my house a big problem is jumping on the couch. I spent time one afternoon with my kids, explaining how I did not want them to act on the couch, and what was acceptable (sitting, laying, etc). If they wanted a cushion from the couch they have to ask. Once I got the couch situation under control, I moved to another situation, then another. It doesn't happen over night, but I have found, that kids need to be taught how we want them act, and sometimes we just assume they know we want them to ask before getting cushions, and get frustrated when they don't, but we never taught them that was what we wanted!
With the fits, which we are experiencing again at age 4, we send our son to his room, because we refuse to give him an audience for his tantrum. If we must, we escort him to his room, and we always remind him to close the door softly. He sulks, cries, sometimes screams, but after 5-20 minutes, he comes out happy again.
For talking back, I would try a time out EVERY time it happens. It is a drag, but consistency does work. My daughter is a little older (almost 6) and hates time out. Make sure at time out he has no toys, lovies, etc. That will help make it a time he does not enjoy.
Good luck to you!