Usually I am hired by attorneys to do mediations, but people without lawyers can also hire me to mediate an issue or case if they prefer. As a Mediator, I am not the lawyer for either side, and I cannot force anybody to do anything. The value of a mediator is to explore possible settlement options for both sides, after privately discussing the strengths and weaknesses of each side's factual and legal positions. Any type of legal case can potentially be mediated, but usually both (opposing) sides need to be motivated to compromise on a few issues (if nothing else, motivated by avoiding the expense, uncertainty, and time delays of contested litigation).
Most cases take somewhere near 4 hours to mediate; many can take nearly a whole day, and every once in a while, a second day of mediation (after certain unknown facts are determined) is beneficial. I charge my standard $300 per hour to do mediations; each person or party paying an equal share.