As far as anyone can tell... yes. There has not yet been found an example of glass that is not glass.I say nay, glass is melted sand, so glass is sand.
YES! Because when you heat the mixture of water and glass beads up at boiling temperature, the water will evaporate and leave the glass beads behind. =-)
Yes, absolutely it does. Also there are different glasses with different hardnesses. Obviously harder glass will scratch softer glass and glass with the same hardness will also scratch.