Yes, he sacrifices himself to save Harry, Ron, & Herimone from the Malfoy manor after they are captured by the snatchers..
Yes he is.
Bellatrix kills him in Harry Potter and the Deathly Hallows
Dobby's age was never mentioned in the series.
Yes he was nice because he saves Harry in the Deathly Hallows
Dobby and Kreacher.
Dobby died in Harry Potter and the Deathly Hallows.
In "Harry Potter and the Deathly Hallows," Dobby the house-elf is killed by Bellatrix Lestrange. During the Battle of Malfoy Manor, Bellatrix throws a knife at Harry and his friends as they Disapparate, and Dobby is hit by the knife as he apparates them to safety. Dobby dies in Harry's arms shortly after, leading to a heartbreaking moment in the series.
Saves peoples' lifes then gets killed by Bellatrix Lestrange.
When Dobby dies. The chapter entitled: "The Forest Again"
End of Part 1 (Chapter 23 of the book.)
He dies at Shell Cottage .
"Dobby didn't mean to kill anyone. Dobby only meant to maim or seriously injure"