Regarding PowerPoint, perhaps have a look here PowerPoint media items show a “Navigation Cancelled” error when running on the Windows Player / PowerPoint brings up an Open Dialog
You do need to have office with PP installed as that’s what Xibo use to open it.
As for PDF module, I believe the default duration is set to 60s - how longs is each page on the screen will depend on how many pages does your pdf has - you can of course adjust the duration.