Gellert Grindelwald was Dumbledore's childhood best friend, so it can be safe to assume that they are around the same age. There is no age given in the books for either of them, but Dumbledore is often described as extremely old. There may be an exact age written on a JK Rowling website or of the like.
Apparently, it is Richard Cant, who is known for his work in British television, including Doctor Who, Midsommer Murders and The Bill. This is however no evidence to back this up. In fact there doesn't seem to be anything about this anywhere else online. So as of yet it is unknown who will play him as an adult.
Sebastian Michaelis kills him.
The duration of The Joy That Kills is 3360.0 seconds.
sasuke kills him after deidra attempts self destruct.
He dies 
In 1945, he defeated Gellert Grindelwald.
Jamie Campbell Bower will play the young Gellert Grindelwald. It is unknown who will play him when he is older.
I think it was Albus Dumbledore.
Gellert Grindelwald, the man he was in love with.
Albus Dumbledore dueled Gellert Grindelwald to gain possession of the Elder Wand. He won that duel, Grindelwald was imprisoned, and Dumbledore kept the wand until his death.
Your question makes no sense. Gellert Grindelwald was killed by Tom Riddle in 1998, in the Numengard prison.
In the movies, he plays the role of Gellert Grindelwald as a youth.
He is set to appear as Gellert Grindelwald in Harry Potter and the Deathly Hallows.
Not sure who killed her, it was an accident during the battle between the three men: Albus, Aberforth and Gellert. No, she is a witch.
Yes, Dumbledore was awarded one for his defeat of Gellert Grindelwald.
into an awkward situation including himself, his siblings and Gellert Grindelwald.