2) Not really. Everyone has biases and by limiting judement to basically one type of group... what you end up with is one bias ruling over all. See for example, france where the Rich and Powerful can basically get away with anything.
3) Again, how would this of been different with the racist white judge who was put in power by the racist white politicians who passed the Jim Crow laws? Once black jurymen got in the jury things got fairer... however, if there weren't jury trials... the racism via Judges who worked with racist politicians would of lasted a lot longer. Kinda like... well France again.
As for the second part...
that's why it doesn't happen in reality! That's what judges are for... to disallow BS evidence and experts that don't pass the test. If you think the American Court room system actually works like court room dramas... you've got another thing coming.
4) What about... bedazzling a judge? Judges aren't immune to this sort of thing afterall, Judges aren't experts on forensic evidence, they need it all explained to them by the same experts. Nearly everything that needs to be explained to a jury has to be explained to a judge.
Bedazzling a judge is exactly how Clarence Darrow got Leopold and Loeb off with only life sentences in what was a surefire electric chair case (granted, that was because they plead guilty initially anyway)
Monster Hunter: pissing me off since 2010.