Arslan,
Yes, the technique of first answering the short questions and then answering the long questions is certainly a valid technique of working your way through the 200 questions. But it is up to you to know what works for you.
My recommendation: You need to purchase a subscription to an online PMP Exam Simulator. Now you can practice and you can test if this technique works well for you.
Remember that every time you mark long questions you may be breaking your rhythm. It may be easier for you personally to select a different style and only mark those questions that you really don't know the answer for.
Your friends cannot tell you this. Only practice can show.
I will forward your other request to our technical support. (Please note that all tech support should be sent to This email address is being protected from spambots. You need JavaScript enabled to view it.. This forum is only for discussing general PMP exam questions.)