Board Thread:General Discussion/@comment-26198344-20150312235543/@comment-25176701-20150313014232

Here's an interview to answer your third question: http://www.buddytv.com/articles/the-100/the-100-season-3-whos-alie-55920.aspx

"Everybody is dead. The only survivor of Mount Weather is Emerson. He's out there, Lt. Emerson, probably to play a role."