General hair care?

I'm curious about this.

I have asian hair. Right now I have it short, so it sticks up and it's a little thin.

All my life (when I started taking daily showers ), I used shampoo daily. I've never used conditioner. This is what happens with my hair when I don't wash and shampoo:
1st Day, no shampoo, no wash: Hair/scalp itches after about 32 hrs (last shower 2 nights before). Some dust/lint/dandruff/whatever.
1st Day, no shampoo: itching isn't as bad. not so much dust/lint/dandruff. hair looks better than it does with no wash, sticks up and evens out again.
2nd Day and after, no shampoo, no wash: dandruff and other crap in my hair. Hair barely itches from this day on, natural oil/grease?
2nd Day and after, no shampoo: still not too much dandruff. hair barely itches from this day on, natural oil/grease?

Also, when I wear any headphones that rest on the top of your head for a few hours, there is a strip of hair that is pressed down and it's very noticeable from the side. I have tried adjusting the headphones to allow for more space at the top near the headrest. That, combined with breaks without the headphones on, has helped, but not solved the problem completely. Is this because my hair is short and sticking up? This even happened once when I didn't wash my hair for a few days, and it was pretty flat.