In most cases, you can't easily use anything they are providing.
There's no easy conversion given the files you were provided.
Powerpoint does not directly transfer to InDesign, in addition Powerpoint typically uses low resolution RGB images.
If the PDF was generated from PowerPoint, then odds are the PDF will also have issues with commercial printing. Not to mention you probably want to redesign things which a PDF doesn't really allow.
Your best bet is to start from scratch with InDesign. Export all the text from the PDF or copy/paste it from Powerpoint. And recreate a layout with InDesign. Chances are high you will need them to supply better, high quality, product images, logos, etc. What is acceptable in Powerpoint is customarily not acceptable for commercial printing.
I don't really understand:
will it be a case of trying to match the style
Why would they hire you if you are merely going to mimic what they already have? Aren't you expecting to create a design? If they just want the PDF/Powerpoint catalog printed.. send the PDF to a printer and let them deal with the issues... why are you even in the loop?
In other words, what is your exact role with the project? A designer? A print liaison?