1. What the hell is magic?
I like Crowley's definition. It's simple and to the point: It's "the Science and Art of causing Change to occur in conformity with Will." Also "every intentional act is a Magickal Act."
2. Can I do Magic ?
You already do, by the above definition. o.o
3. Is it dangerous
It could be, if you prefer.
4. Is it a negative/dark practice?
Only if you take or use it that way!
Negative/dark and positive/light come from a dualistic way of thinking. For brevity I will say that Taoism and the Tao Te Ching make a pretty convincing refutation of the ideas of good/bad as being anything other than arbitrary opinions. But, having said that, I would redefine "good" and "evil" as "service to others" and "service to self," respectively.
So my question would rather be, are you using magic to serve others? Or are you only using it for yourself, at the expense of others? It's possible to serve others and yourself at the same time, or to serve yourself in a way that doesn't exploit others.
5. Can it bring happiness and light?
That's more of a philosophical question. I personally think that if you need reasons to be happy, or if you have to do stuff to be happy, then that's not real happiness and it won't be permanent. You have to be happy for no reason, to really be happy. But yes magic could bring these things I suppose.
I think this is a great way to explore ideas, with sets of questions. It can become a game of trying to ask the right questions in this case, because magic is a very broad and diverse subject, and if you can find the core of what it's actually all about then you've found something important and relevant to everything in life.