Dumbledore doesn't really use a spell. He just puts the Stone in the Mirror of Erised.
It is spelled Dumbledore.
That is correct.
Dumbledore uses the non-verbal spell to cast fire around the inferi. He only talks to Harry once the spell saves them.
When Dumbledore realizes that there are intruders in the Astronomy Tower, he immediately put a Stunning spell on the invisible Harry in order to hide him. When Snape kills Dumbledore, the spell binding Harry vanishes, making him sure of the fact that Dumbledore is dead.
Severus Snape killed him with the Avada Kedavra spell.
That is a very good question. Unfortunately, we don't know what the Dumbledore's strongest spell is. I am sorry, but this question doesn't seem to have an answer, unless of course you ask J.K. Rowling.
The Hogwarts headmaster (Harry Potter books and films) is "Professor Albus Percival Wulfric Brian Dumbledore."
Albus Dumbledore was hit by the killing curse, Avada Kedavra, which was cast by Severus Snape.
Igneous is formed when a hot liquid rock cools down and becomes hard.
The name of the character in the Harry Potter series is spelled Dumbledore.
The correct spelling is protective.
The hard igneous rock is spelled "basalt".