It depends on what you mean by a "relationship." If you mean a sexual relationship, as far as I know, every state has laws making it a crime for adults to engage in sex with minors. If it is purely a friendship I don't think if is forbidden.
Teachers are not allowed to have relationship with pupils because they are considered as the parent figures of pupils while at school.
Yes but at a certain extent.
No, unless they have a very good reason.
Yes. Of course, they can't deny pupils the right to eat lunch, but other than that yes they can.
In the sense that a teacher can say "if you do not behave I will place you in detention" Yes, of cause they can.
No mobile phones should be allowed during lessons. Not by the teacher and not by the pupils.
yes
no.
Teachers evaluate pupils so they know what level of skills they are on.
Teachers care for education because they usually like the pupils and enjoy teaching them . Also its their job and they want these pupils to have a bright , great ,future!
Well, there are many reasons why the schools close. Travel is a huge issue. Teachers and pupils/parents can't make it to and from school. Also, sometimes the heating can break down so the pupils are instantly not allowed in school.
To set a good example to their pupils.