I forgot to include the following sentences.
3)What kind/type of school do you go to? I go to a private school.
4) How do you spend your free time?
What do you do in your free time?
5) How far do you walk to school? How many kilometers do you walk to school? I walk 3 kilometers to school.
6) When do you arrive at school? Do you arrive there on time?
7) How much water do you have in the house? What do you like to do (doing) at weekends?
8) They don't eat enough vegetables. How much green food do they eat? How many vegetables do they eat?
All are fine, except in #7 -- not "doing."
Also for #7, say "on weekends" instead of "at weekends".
To answer each of these questions:
3) What kind/type of school do you go to? I go to a private school.
To find out the kind or type of school someone goes to, you can simply ask them directly. In this case, the person has mentioned that they go to a private school.
4) How do you spend your free time? What do you do in your free time?
To find out how someone spends their free time, you can ask them directly. This is a personal question and can vary from person to person.
5) How far do you walk to school? How many kilometers do you walk to school? I walk 3 kilometers to school.
To find out how far someone walks to school or any other location, you can ask them directly. In this case, the person has mentioned that they walk 3 kilometers to school.
6) When do you arrive at school? Do you arrive there on time?
To find out when someone arrives at school or any other place, you can ask them directly. In this case, you are also asking if they arrive on time, which means if they arrive at the expected or desired time.
7) How much water do you have in the house? What do you like to do (doing) at weekends?
To find out how much water someone has in their house, you can ask them directly. The second part of the question is about what they like to do on weekends. To find out someone's interests or hobbies, you can ask them directly. These are personal questions and can vary from person to person.
8) They don't eat enough vegetables. How much green food do they eat? How many vegetables do they eat?
To find out how much green food or how many vegetables someone eats, you can ask them directly. In this case, the statement implies that they are not eating enough vegetables, and you want to know how much green food or how many vegetables they actually consume.