Is there going to be a second thor movie?
Thor: The Dark World will be the sequel to Thor.
No, it is not true. According to the comics, Thor is the strongest avenger. In the 2012 Avengers movie, Thor nearly beat Hulk, but Hulk got distracted and started beating up an airplane. Thor is probably strongest because, Thor has the indestructible Mjolnir. As you saw in the movie, Hulk could not pick up the Mjolnir.