Hiding the URL bar is not possible as this would conflict with scrolling the PDF itself.
But Pinch zooming is on my todo list. There are several "workaround solutions" for this, as PDF.js does not offer this officially. I'll add the best-working as an optional feature (configurable in the Addon configuration).

Would be better to discuss something like this in an GitHub issue...
I had a look at the PDFViewer4Android addon. This is also very well done but it also has some issues that I already have fixed in my version. I have some workarounds with make my solution a bit more robust to avoid PDF files still getting downloaded.

Pinch to zoom should be possible and I will have a look at a possible workaround to hide the address bar.