I am keen to prepare for the PMI-RMP exam but need some advise on the following:

- what are the Books/Texts to study?
- where can I find the best practice questions that are closer to this exam?
- are there mathematical questions and formulas to remember?
- average time needed to prepare for the exam?
- is this exam more difficult than PMP?
- any other advice would be appreciated.

Thank you in advance.