In the morning, I usually greet my family or friend with "ohayou(gozaimasu)" . in the afternoon and evening, I say "konnnichiwa", but sometimes say "ohayou" to people I meet for the first time in the day.
Is it different for different people? How so and why?
Yes, it is. People use many different way of greeting case by case or with individual. I think that the differences are depend on their living environment which they have had. And also, the differences depends on each culture or religion.
Do you touch people when you talk to them? Why? Or Why not?
I sometimes do, but just for close friends. In my view, it is normal to talk as touching my friends, but I don't mean doing it in particular. If I am touched by someone who I don't know well, I don't feel comfortable.