Chanmadd, Tom, and Cobranip, all excellent questions;
Chanmadd you have to realize that this is a StreetBeast kit and the manual, to say the least, SUCKS! This isn't the first time during the build that something in the manual would be totally opposite from reality. Unfortunately SB has gone out of business (for the umteenth time) and has not been reincarnated this time, so I can't call them anymore. They were supposedly rewriting the manual when they went south.
Tom, no metal plate, only directions in the manual of where to drill the holes in the upright and pictures of, supposedly, how to mount the hinges.
Cobranip, the hinges are identical to each other, the only difference is the way you put the hinge pin in. I've compared them 50 ways to Sunday and confirmed this.