So according to the statement be many Christians, Moses, Buddha, Muhammad, Gandhi, Japanese inventors, Julius Caesar, and many others may burn in hell instead. Please do not report this question, I am only asking for religious guidance.
Jesus is the one who will determine everyone's qualification for salvation.Of course He will reject those who reject Him but He will have to use standards of morality for those who never heard of Him.
Yes it is true. Anyone who does not believe in Jesus as their savior will not go to Heaven. BTW all Christians believe that Christ is their savior hence the term CHRISTian, so Christians will not go to Hell.
Of course it is not true. This is only a protectionist teaching. People who believe this is either very naive or stupid to think so. Of course believing in a religious teacher like those you mentioned gives you a better chance because of following on their teachings to do good.