Effect of fixed image

I have on homepage parallax scrolling effect on my site. (I hope, this is the right name of the effect)
You can see: http://model.website-easy.club/
I have some questions…

  1. How to achieve this effect on mobile devices?
  2. How can I set up image sizes and number of columns of images on mobile devices.
  3. Is it possible to make a slider of images of each portfolio scrollable on touch screens?(you can see here: http://www.joakim-karlsson.com/)

Hello,

Please create a separate topic for each of your issues in order to make it easier to help you.

Kind Regards, Roman.