Continuity mistake: The bomb that Garret wears has four kryptonite section, one at each of the corners, and each section has three distinct pieces. The pieces glow only from the center core and the outer edge is only green colored and is not glowing. When the shot switches to the CG shot of Garret falling, The camera passes over and grabs the bomb and now the krptonite has a uniform glow and there are now the one block on each corner does not have the three individual pieces.
Continuity mistake: Garret is shot in the chest and the bullet is shown as hitting on the right side. Then, in the special effects shots as time is stopped and Garret is in mid-fall, his bullet wound is now on the left side of his chest.
Answer: No, there is no such character in the comics. He's a "meteor-freak" like all the other baddies on the show. The sound has something to do with him vibrating his vocal cords very fast to create a high-pitched squeal.