Hollywood in India: Protecting Intellectual Property (Cases A and B)

How can we identify plagiarism in a movie? How about software, images and books?
Is Partner a plagiarized version of Hitch? How can you tell? Both movies are about a dating coach, i.e., a man who helps other men make an impression on women they wish to date. Why cant we have two different movies with the same idea?
Is the same idea going to generate the same audience experience when implemented in two different settings or two different languages?
Consider the issue of plagiarism in a book. At how many exactly same words to you draw the line? How many lines of computer code need to be the same to judge that one piece of software is a plagiarized version of another? Is such a bright line really necessary?
Now you have these two movies: My Name is Khan is about an autistic man who falls in love, who wanders all over the United States in a quixotic quest, who quotes his mother all the time and gets to meet the President of the United States. Forest Gump is also about a somewhat different type of person, who falls in love, who happens to run all over the United States, who quotes his mother a lot and gets to meet the President of the United States. Is one character a plagiarized version of the other?
How can a movie studio prevent plagiarism?
What strategies should Fox Star adopt to combat potential piracy of My Name is Khan? Please consider the costs and benefits of each strategy you suggest.
Questions should be thoroughly analyzed and answered in a total of 8 to 10 pages.