a) Most of the comments here are accurate, you need to be in a fully profiled environment, that will fix any issues that are fixable with your process/equipment limitations (other than education on the subject).
b) You can't expect pure-tone b&w giclee results from a CMYK solvent machine, they're different beasts.
c) You are correct, black inks have tones, usually green, they're almost never pure. That's why pure-toned grayscale giclee printing is the hardest and most expensive type of photo printing and is a super specialized niche. Proper calibration will help but you'll never come close to a b&w specialized giclee printer running carbon inks--and even if you converted your machine over to a b&w inkset (PiezeoTone maybe) you'd lose the ability to do any color on that machine.
b) You can't expect pure-tone b&w giclee results from a CMYK solvent machine, they're different beasts.
c) You are correct, black inks have tones, usually green, they're almost never pure. That's why pure-toned grayscale giclee printing is the hardest and most expensive type of photo printing and is a super specialized niche. Proper calibration will help but you'll never come close to a b&w specialized giclee printer running carbon inks--and even if you converted your machine over to a b&w inkset (PiezeoTone maybe) you'd lose the ability to do any color on that machine.