To loop a PowerPoint slideshow, you'll need to enable looping in the program's "Set Up Slide Show" menu.
You can insert a PDF into a PowerPoint either as an object, and then set it so it opens when you click it.
You can change the background to anything you like if you're using Powerpoint to create presentations: a picture, a color, a gradient, or even an in-motion video. You'll know the best background for ...