The CSCS can only be taken if you have a four year degree in a health related field, the ACSM HFI test is the same way. I am taking my CSCS the end of July and as for a Nutrition Certification I would recommend ISSN.
You can look at sample questions on the CSCS website. The ACSM HFI I just took was hard due to the fact that it had clinical testing plus everything that goes into a normal CPT test.