He was still known by his birth name, Tom Riddle.
Voldemort's symbol - the skull with the snake coming out of its mouth - is called the Dark Mark.
Tom Riddle is Voldemort. He changed it to Voldemort just before he left school.
Voldemort: Harry Potter's archenemy. Dumbledore: The director of Hogwart's School.
Horcrux
Horcruxes.
Harry's enemy is initially Voldemort, however in school it would be Draco Malfoy.
He goes below the school, and finally defeats voldemort to get the philosopher's stone, stopping voldemort from returning to full power.
No. Voldemort gained his first followers at Hogwarts. Although it is unknown what year Professor Quirrell was born in, he certainly wasn't old enough to be have been at school with Voldemort. Quirrell met and joined Voldemort in 1990 during a year long sabbatical.
Because there are seven school years in Hogwarts. (Unrelated to this, Voldemort made seven horcruxes.)
"You-Know-Who" or "He-Who-Must-Be-Named"
When Harry and Voldemort duelled, their wands, which share a core of a feather from the same phoenix, were linked in the Priori Incantatem effect.
Krum, becuase at his school, the symbol was written on the wall by gregorvitch. He was the feared one before Voldemort came to power. In the 7th book he was killed by Voldemort in Azkaban.