if you are not called into court, you will not have to testify
Absolutely not, and they will be charged with contempt of court if they show up to testify in that condition.
no
The circumstances under which one would have to testify in court will vary according to the jurisdiction. In the English courts a witness needs to be cross examined, so that if their testimony is key to the case, they can be subpoenaed. This compels them to attend court and testify.
Court testimony is the right to testify in court of what he/she saw during the incident.
No set number.
Yes.
This word has been recently used as a challenge to express sympathy; i.e, "Testify...".I have been called to testify in court as an expert witness.
Generally speaking anyone can be asked to testify. Though someone can be ruled as medically or mentally unable or incompetent to testify.
No, not unless you are subpoeana'd by one side or the other. A person can voluntarily testify without being subpoenaed as long as one party or another calls the person as a witness. Expert witnesses are hired to testify in court; therefore they also testify without being subpoenaed.
Yes, if you do not show you are in contempt and can be arrested.
Yes.