You should apologize. It makes you feel better and the other person feel better.
Nothing - if the apology was sincere. If it wasn't sincere, wait until you are actually sorry for what you have done, and apologize again, properly. If it was sincere then there is nothing else you can do, the problem is now the other person's.
whenever you are ready.
A sincere apology would be a good start.
you either say you accept or you dont. you either say you're sorry too, or not accept their apology. When someone is really apologizing, they are putting themselves in a vulnerable position. If they are sincere, and you are willing to take the apology, say you accept, and either shake hands or make some conciliatory move. If you are not willing to accept, either because the offense was too great or the apology too late or too insincere, then civilly tell the person you appreciate their effort but the you do not feel it was enough/sincere or what ever reason. Then walk away and get on with your life. Any other response (say the movie dramatic effect of a slap in the face) would put you in the position of the offender and require an apology from you for your behavior.
if someone was amazed, surprised or disgusted
It depends entirely on the circumstances. HOWEVER a humble, respectful and sorrowful apology will always help alleviate a situation. It sounds like a good idea if your apology is sincere. Don't apologise if you have been right though. Many people do this just to keep a girlfriend or something. Many girls actually expect to have an apology even if they know they have been wrong. This is just sooo wrong.
Yes. Yes. Some people are very sensitive to "abusive" language. Many times a sincere apology will help to mend the ways.
Abuse is abuse. Once someone strikes you, all respect is lost. No matter how sincere the apology is after the fact, they can and will strike you again. I have been there once a long time ago, and know someone that has recently gone through it. Think of yourself and get out of it while you can!
The right response should be: "I have accepted your apology". Or "I have noted your apology"
Being a girl, the #1 thing I like to hear when I'm mad at someone is a true, sincere, apology. Usually that fixes the problem. If that doesn't work, try saying I'm sorry again and buy her a small gift. Something that she loves.
Dusted and Disgusted is a song, well, a rap song, from E-40 featuring Tupac Shakur. Dusted and disgusted tells a story of how women can't be trusted and how disgusted the singer is with them and how he dusts those that cross him. To dust someone is to kill them. So, it's not an idiom, per se, but a song lyric.
He is probably not mature enough to be sincere -- many people never get to the point where they can be sincere with other people, which is a sad fact of life. If you want a sincere friend, you will need to either wait for him to grow up emotionally, or find someone else.