I think they are all part of some protoss hero unit. (Aside from the photon cannon.)
They just look like armor or weaponry. It looks like he could have some whip with a claw or something. Lots of jewelry.
Could it be... Xel'Naga?
None.
Good find though!
Zoan -- of course it isn't full understanding. You could ask "is the mechanism by which this counterexample blows up the ONLY mechanism possible for an initial configuration to blow up?"
Zoan -- Heinermann
NudeRaider -- I only heard about it, didn't any news article, so what did it do then?
Heinermann -- it also didn't solve that problem but hey as long as the investors are pleased
NudeRaider -- I have no idea tbh. All I know no human was ever able to solve it, but there's at least a few that beat portal 
Oh_Man