Hello SVS,
Here are my answers for you:
I am using PM Exam simulator for practice exams.Do those exams simulate the real exam 100%? specifically in real PMP exam
The PM Exam Simulator is trying to simulate the "real" PMP exam as much as possible. The % of questions that you get from each process group are equal to what you will have on the real exam.
1) If I answer a question correctly, but leave it marked becaue I am not 100% sure, but if I do not get time to review the same and make it unmarked,will it count as correct answer?
Yes, because marking a question has no influence on your score. If you answer a question correctly then it's counted as correct.
2) Can I go to Previous question after answering the current question as in Practice exams?
Yes. You can go back and forwards until you click the "end exam" button. Just like in the real exam.