1. In guides it was said that it was a laser, and in the series it is said that.
a laser attack with incredible impact.
2.13 says that he can absorb aoyama's light, since he has the black hole quirk (but of course this black hole is not as harmful as a real one)
the black hole absorbs light .
3.
toru hagakure can reflect that(the explanation is that toru is invisible because she absorbs light,but when the light hits it directly it will be visible and reflect that light)
4.Aoyama does not move at the speed of light, but he uses it to attack, since he can damage any object with the attack, but he will never use it to move at that speed (like when he uses it to move, he only uses it to move but he didn't move at the speed of light, because it doesn't work like that)