All the photos are pretty decent, but just a personal dislike of mine is using a low f-stop in a black and white photo, the out of focus areas create an ugly blur.
(really noticable in picture number two on the back right sholder)
I think you did a great job with capturing the subject. I feel you captured the essence of the subject...like I know a little something about all of them just by their picture. The technical aspects need a little help...particularly in lighting, and a little PP. Keep it up
The expressions aren't bad, but I find the lighting really distracting in almost all of them. Its really harsh or not contrasty (yes thats a new word) enough to me. Some post processing would help in some I believe
Here ya go. I did some curves adjustment, skin softening, eye enhancement, burn on some of the hair to add some detail, brushed up under his right eye a bit and did a highpass filter.