Describe Dr Van Helsing and explain why he is important in the story. What do we learn about vampires throughout the story?

Dr Van Helsing was Arthur’s old teacher. The text talks about him like he was a good person because he helped a lot to the four friends (Lucy, Arthur, Jonathan and Mina) instead of saved persons to were attacked by vampires.
This old teacher is very important in the story because he was the person who tried to help Lucy when she was changed to a vampire and obtained that Lucy could rest in peace. Also he could save Mina when Count Dracula made her a vampire. The Dr. hypnotized her every day so Dracula’s power was not as strong as it used to be. When she was hypnotized she told to the teacher and to Jonathan things that were related to Count Dracula. With Van Helsing ideas they could save Mina.
And the most important thing that the teacher made was to help Jonathan and Arthur to killed Dracula.
We learn about vampires that they rest during the day and at night they go out to look for blood, when they take the blood of a person, this one change into a vampire. Also we know that putting a circle oh holy bread around a person, is safe to be attacked for a vampire.
At least we learn another thing about vampires; to destroy them we have to find the place where they rest and put wooden stakes trough their hearts and then we have to cut off their heads.