1. I had seen 50 Questions each under 5 domains.
Apart from this there were 2 full length 200 exams.
Are those 50 x 5 questions included in the 200x2 questions or both are separate ?
The 50 questions set for each domain are coming from the database of 900 questions, and when you practice them multiple time, there is a high probability that you will get new questions.
Full-length questions also come from the database of 900 questions. However, these 400 questions (200 for each practice test) are fixed thus each time your practice, you get the same set of questions.