Some questions about light. One is,.is there a limit to the amount of light (photons) in a given volume? What I mean is, does light have any density and could you fill a box up with light?

Second question is could we theoretically create a cube lined with mirrors to bounce light indefinitely?

Third question is when light reflects off a mirror, doesn't it hit light that is going into the mirror? Why isn't there a collision that would distort the image?