My impression is that the each line is shorter on the screen. So an article of 90 lines is not much. As to how much time on each question, it really depends. I normally spend less on CR than on SC or RC. If you are particularly strong in one type, use that wisely to your advantage.
There are 4 RC articles for sure, with 3-4 questions each. CR is normally 11-13 I think. The rest will be SC.