Yes.
No. Supernovas are cataclysmic eruptions from massive stars that have come to the end of their lives. See related questions
A Pulsar. See related question
Supernovas are the explosions of large stars in space.
There have been about 15 observed supernovas [See Link] from as far away as Australia China, Europe, America. As many are visible to the naked eye, I would say that all countries have observed them, whether or not they has been recorded.
no
Stars do not create supernovas. Supernovas happen to stars. A supernova is when a star, bigger than our own sun, explodes due to the lack of gas they need.
We do not yet have enough experimental data to answer the question precisely, but there have been about one per century in the Milky Way (at least, the part that we can see). We know that there are supernovas in other galaxies, but they are detectable only through large telescopes.
Star Dust from supernovas is what makes technically 'everything' in the Universe.
They are not. A supernova is an explosion of a star. Blue stars usually end their lives in such explosions.
In space.
A great energy and light is produced by the supernovas. Therefore, a great number of photons is produced.
Humans see with their eyes