How would one find downloaded APK files on a Note Pro? | would like to side load one to my new Note 4 as I think the tablet version would work better than phone version which uses the now extinct menu button.
It depends on what you're using to download it. The Download folder in the internal SD card is the default location, but a particular browser may be set to download to a different folder. (Or you can download it on a computer, which gives you more control of where it goes, they copy it to where you want it on the phone.)