CPDPs are basically gift marks.
For some sample questions, you can have a look on the CASA website, but any study material you have, will have practise questions in them.
Lionel, Nathan, Rob and Gavin all give you a good feel for how the actual questions will be worded, and what they're looking for. If you can do their questions accurately, you'll do the exam accurately too.
What you need to do, mingalababya, is be accurate on the first time you crunch any numbers. Don't go back and check, unless you really need to. If it's just a confidence thing, try a few practise questions without going back and checking, and see how good you can actually do it. Saves a lot of time when you only have to do each question once, instead of twice.