How did this material world come into existence if the ultimate reality is voidness? Okay, I know that anything that come into existence has a cessation..

So, how did this world of suffering begin?

Or, if you say it never began and it's ever existent, why would it need to exist?
What's the cause that's made this material world?

If you say that the cause is the Karma of a being, how come Karma come into existence? (By existence, I mean to ask why does Karma exist?)

What's the ultimate cause or factor for existence or emergence of corporeality?

I'm not trying to argue or quarrel, but I'm searching for answers from the point of view of Buddhism.

I accept that these kind of questions and answers doesn't lead to cessation of pain or suffering, as the Buddha said, but I'm just eager to know :)
Buddhism does not answer such questions, since they do not lead to Nibbana. The Buddha said himself, that he teaches only the cessation of suffering.
It's not that these questions are not important or interesting, they certainly are, but they will not lead one to Nibbana. They will only distract and agitate the mind, leaving it unfit for practice.
If you really want to know the answers to these questions, not only intellectually but experientially, then you have to become a fully enlightened Buddha (Sammāsambuddha). Then you will be able to know everything, that there is to know.
The questions you mention, fall under the &quot;Four Imponderables (Acinteyyas)&quot;:

The four imponderables are identified in the Acintita Sutta, Anguttara Nikaya 4.77, as follows:
The Buddha-range of the Buddhas [i.e., the range of powers a Buddha develops as a result of becoming a Buddha];
The jhana-range of one absorbed in jhana [i.e., the range of powers that one may obtain while absorbed in jhana];
The [precise working out of the] results of kamma;
Speculation about [the origin, etc., of] the cosmos is an imponderable that is not to be speculated about.

These are questions that the Buddha did not answer. Only a fully enlightened Buddha can know the answer to these questions and the questions themselves.