The second season aired on September 13, 2013.
Season 4 of The Legend of Korra is called Book 4: Balance, and the season premiere is on October 3, 2014.
Season 1 of The Legend of Korra was called Book 1: Air and the season premiere was on April 14, 2012.
The season premiere of Book 4: Balance of The Legend of Korra will premiere on October 3, 2014.
The third season of The Legend of Korra (Book Three: Change) premieres on June 27, 2014.
Season 2 of The Legend of Korra was called Book 2: Spirits and the release date was September 13, 2013.
Yes, there are going to be 4 seasons and a total of 52 episodes. Season 4 will be the last season of The Legend of Korra, which will probably premiere sometime in 2015.
No, Book 4: Balance is the last season of The Legend of Korra.
Legend of korra season 3 is going to be called "Change".
The title of Legend of Korra season 3 is called "Change".The Legend of Korra will remain focused on constant elements of human experience.
As long as Korra doesn't die in the Avatar state, then yes. The cycle is Water, Earth, Fire and Air, so when she dies, someone in the Earth Kingdom will be the next Avatar. The real question is whether or not the creators will animate the story about the next Avatar after Korra.
Yes, Mako and Korra will be together in Season 2.
It has not been announced whether the Avatar series will continue after The Legend of Korra. If a sequel does get planned, it probably would not get announced until The Legend of Korra ends which will be sometime in 2015 after season 4 ends.