Click on the 6 small squares icon on the top right of your home screen, that's the apps icon. On the app screen, find 'file manager'. In the file manager there is a folder called 'downloads'. You can open the files there. To make it easier, when you get to the apps screen, press and hold the file manager icon to move it to your home screen.
As far as tracking replies, I believe you can just click on 'my account' or your screen name and there should be an option to see your posts.