He thinks (and is true) that he has lost all powers and is out there biding his time, until he will return as he didn't have enough human in him to die.
Harry thought it was either Professor Snape or Lord Voldemort under the cloak. It was actually Professor Quirrel and Lord Voldemort, who were sharing a body.
The Norwiegian Ridgeback dragon Hagrid got from Voldemort at a pub in the 1st book.
Dumbledore sent him to try and convince them to join forces in the battle against Voldemort.
Actually now that I think about it he didn't see him until the 7th book near the end where Voldemort is bragging to everybody about killing Harry and then Hagrid flips cuz he can't find Harry's "dead" body.
Lord Voldemort, or as he was known then, Tom Riddle.
Harry Potter was taken away after Voldemort had tried to kill him by Hagrid to Dumbledor and the Dursleys. Sirius Black was the one whom lent Hagrid the flying motor bike.
Among the many facts that Harry Potter learned from Rubeus Hagrid are that Harry is a wizard and that his parents were not killed in a car crash, but murdered by Lord Voldemort. Throughout his years at Hogwarts, Harry learns others things from Hagrid who becomes his Care of Magical Creatures professor for three years.
Voldemort entered harry's body for a few moments before retreating.
Rubeus Hagrid's mother was a giant named Fridwulfa. She left when Hagrid was three years old and returned to the Giants where she had another son. Fridwulfa died several years prior to 1996.
During Harry Potter and the Order of the Phoenix, Hagrid and Madame Maxime were in the wilderness trying to gain support of the giants before Voldemort could convince them to aid him. Hagrid actually appears later in the book when he returns to Hogwarts with his giant, half-brothe, Grawp, who remains hidden in the Forbidden Forest.
Yes. Shortly afterwards, Professor Quirrell attempted to steal the stone from the vault. Due to his failed attempt Lord Voldemort decided to share his body to keep a closer eye on him while they worked to steal it from Hogwarts.
Hagrid told him he was a wizard.