Day 7 post circumcision- is it normal for minor bleeding 2 occur through thick black scab on underside of penis?

Circumcision. Surgical incisions may take up to a week to heal. Given the nature of the skin around the glans penis, there could be a small patch of skin that is "necrosing", which is probably the black that you see. If that is part of the remaining foreskin then there is no need to worry as it will just fall off. But if it is part of the normal penis skin, then I recommend having it evaluated by your doctor.