Good Riddles

Question: Fifty is my first, my second is the third in fourth, and my end is the end of an ending. With a nut I become a nut that isn't, and without one I move.

Question: I cannot speak but i tell everything.Im not a tree but i have a leaves. I have hinges but neither not a door nor a window. Who am i?

Question: Farrah left her key under the mat and when she came back she lost it.The painter said he painted the wall ,the security said she didn't know, annd the janitor said he cleaned the floor. Who took the key?

Question: I can be seen and heard miles away, only show my position for a couple of seconds, but if touched it can kill you instantly.

Question: If the ends justify the means, then what may be said about social media?