It was the part of Voldemort's soul that was inside Harry Potter.
Yes, Albus Dumbledore was a mentor to Harry and could be considered as something of a grandfather figure.
When harry dies he comes back to life after talking to Dumbledore. Dumbledore told him to get on the train or go back to real life. Harry returns to the real world The curse killed the horcrux in Harry, not him.
Albus Dumbledore sent that Howler.
Dumbledore knew harry had to tell him something because dumbledore knew what it was but if Harry would tell Dumbledore. I guess when Dumbledore asked Harry if he had something he wished to tell him, he wanted to know if there was something that Harry wished to tell him. (Of course I can be wrong, but this is quite possible, is it not?)
Dumbledore suggests that he loves Harry as a son. Dumbledore was a role model for Harry.
It is spelled Dumbledore.
So Harry would not interfere in the plan Snape and Dumbledore had agreed on.
Ariana Dumbledore.
Albus Dumbledore is male.
No Harry is not related to dumbledore.
You can find dumbledore's office by going up the steps that move until you see the griffin gargoyle
well dumbledore sends harry a letter by owl in the beginning. throughout the year harry gets multiple letters from dumbledore but he uses people to find him, not owls.