Based from the information you are loosing hair at very young age is mostly related to heredity or from taking extra steroids
for building body (anabolic steroids , testosterone
excess) leads to hair fall
(1) Hair fall about 100 a day is pretty normal and nothing to worry, but as you have mentioned it seems that you have more hair loss then the normal. The cream based solution called "MINOXIDIL" can be used to sprout new hair and will help in increasing the growth of hair. More over stop using the steroids for the body building ( incase of using it) will be a great help.
(2) The itching in the head / scalp
is mostly due to dry skin
and fungal infection
commonly known as "DANDRUFF" which can be treated by SELSUN
shampoo which has anti-fungal component and will help to deal with it.
(3) About GREY HAIR - its genetics nothing can be changed, the hair producing cell are genetically programed and will stop producing the black pigment after the program is all done , it may be stimulated again by massaging the hair follicles with oil, but result is variable and not a properly reproducible. So the viable options remaining is the artificial coloring hair with dyes or heena.
Hope it helps.
Dr. JAY PATEL