First of all, I will not write any details about the exam here because those are tend to change in time. I suggest you go check the info at the end of this page for general information about the certificate.
For your questions, once you sign up to the exam you will get emails from mendix and mettl(examining partner), those will explain everything you need to know.
Hope this helps!
Hi swarojani , for rapid exam you have no limit of time, you can as much time as you want.
Best luck for exam.