I was just trying the wp8.1 emulator (from the SDK RC released yesterday), and these features are just not there. As far as I could see, you only get a "file picker" when you try to upload something from IE11 (that is very good improvement) where you can see folders like "photos", "documents", "music" but also a "download" folder, that I assumed was where all the other type of file should be stored. But still, if you try to download a .exe file, IE11 blocks you with the "not supported" stuff. AND, if you tap the attach button from within a new email, you still find yourself wandering inside the photo hub with no possibility to pick anything but photo (or video)...great disappointment for me. I hope I just didn't get it right, and maybe I was missing something using the emulator...