Hi Mohammed,
I suggest you to try few mock exam simulators that are available on the net and also that comes free on a CD with books such as Kathy&Bert's book for
SCJP.
Also, do not forget to try Ashok Gupta's Mock Exam
Applet, which I feel, is quite near to the look and feel of what it is in the real exam. (For example, it has an "Exhibit" button to open source code in a new window, if source code is longer than 3 or 4 lines apart from the standard buttons Next/Previous/Mark/Review Item, etc.)
However, you can also take a sample exam (like a Tutorial) before taking the main exam in your prometric center, so as to get the feel of the real one. But this is possible only few minutes before your real exam.
Regarding your second problem, I suggest you to either login to the prometric site with your id and try to update your profile or call up their help-desk service in your country. I am sure, you can sort this out.
Good Luck!
cheers,
~NRao