Show / Hide Div Layer / Change Link Color / When Radio Button Is Selected

I am trying to develop an exam system.Find my code below.I request you to copy the code and save it as an html file .I have 2 problems:

1. Kindly notice that when the quiz is loaded,it shows both the questions by default.I want only question 1 to be visible when the quiz loads.What happens presently is that ,both questions are visible even after I click on the link
Q.1( referring to question 1).However,when I click on
Q. 2,then only question 2 can be seen and then(after clicking on Q.2) if I click on Q.1,then only question 1 can be seen

What I want is that when the page loads only question 1 is visible.Then when I click on Q.2,I can see only question 2 and when I click on Q.1, I can see only question 1.I later plan on adding many questions,so it should be a general solution rather than a solution good only for 2 questions.

2.Also,what I want is that,if someone selects any of the answers of a particular question,it's link color should turn green to indicate to the user that he answered that question.So for,instance,if I select an answer to the first question(select one of London,New York,Seattle,Washington,Chicago), the link Q.1 should turn green.