Database design questions

I have few questions that i would like to ask:

1. If i am creating a system whereby there is a hierarchy of users (i.e. students, teachers, manager). should I store this in one table or three? avoids having to self join again and again to get relevant info?

2. if i need a system whereby I can set some questions and answers, or questions with multi-choice answers. How best should I store them?

Class_id, question_id,question,answer (for Q&A)

class_id,question_id,question,answer (for multiple choice Questions)
question_id,choice

Iwould do the following:
#1 For question1:
Store them in the same table but with a usergroup,

Make a second table to store user groups


*this allows you to add and alter groups or names and sort them by number


#2 For your second question.
I would make 2 tables (questions and answers)
and interlink them with their corresponding id's

The reason why you want 2 different tables is because you would otherwise duplicate data, which is unnecesary.
table questions:
table answers: