Some short answers:

Login: I don't think there are any. Vendors can choose to hide/show Android settings.

My Settings: If in doubt, always check SlideMe.org

USB Mount: once the cable is connected between Mac and eDGe, on your eDGe go to the Notification that appears an tap it to mount the eDGe as a drive. Unmount it the same way before disconnecting the cable.

Library: this is a custom enTourage feature that is specifically designed to implement their vision for linking documents. The files are stored in \sdcard\.edge\.esi-content and are tracked via an internal database. Do not mess with the files in this protected location! You can only use Tags to organize them in the UI, not folders. When you add a file to the Library, it copies it from the source location to this protected directory, therefore do not retain the source file in Internal Storage or the SD card (but be sure to have a back up on your Mac or on a USB memory stick, etc.). You only need to add a file to the Library if you want to annotate a document. Do not add music, picture or video files to the Library as this is rarely necessary.

Reader: no. The Journal app actually has the capability but enTourage had technical problems getting it to work, so the feature remains unavailable.