if its happening at work, you can get them sacked! go to your manager
Yes if they get it on tape and take it to the pollice your toast
prove to the court that you are likely to have success on the merits (substantial chance of prevailing in the case)
Only if they are threatening you or physically/sexually harassing you. You should call your local police department for more info.
Let them know that it is not ok to talk to you in that way. Tell them that you will not be around them anymore if they can not address you in a respectful way. If it continues, you might have to...
punch them