Is it possible to have two apps side by side with each being 50%? It's easy to do this with two desktop applications like word and IE, but I'm trying to have a word document open and a PDF open at the same time. Not sure if there's a pdf viewer that opens in the desktop.
No, unfortunately you can only do that in desktop. Any Modern UI Apps must be a small bar on either side plus the main app. You can try opening the PDF in the desktop web browser and Word in Word and then doing 50/50.