For reading all the questions how much time I should spend?
Ideally, you shouldn’t spend more than 15 minutes in reading the passages and the questions. If you rigorously maintain time, you would get 45 minutes to answer 40 questions, so you should try to write each answer within a minute or less. You must stay prepared for that, otherwise, you would have to run short of time. Keep in mind some question would require a longer time to complete.