A: Graded (sometimes called adapted) books are simplified classic books or written from scratch ones using simple English. Such books are graded by levels. The lower level - the simpler words and language constructions are used. Using graded books you can enjoy reading without much efforts and slowly increase your vocabulary. In every next book you will find some new words for you that will be used it this book several times in different sentences, so you can understand their meaning and remember them at once.
A: If you are only began to learn English you should start books from the first level too - Elementary. But if you has been learning English for a while, you can try Pre-intermediate and if it too easy for you - try Intermediate and so on.
A: Unabridged 'level' means that the book is not simplified in any way - it's original version from the author.
A: You can try of course, but if your own vocabulary will contain words from graded books only - unabridged ones will be very hard for you. There is a big distance between advanced graded and unabridged books. You should learn the full grammar course of English before try originals. Also after graded books, you could try magazines, journals and news at English language - they are much easier to understand.
A: Unfortunately, you can't. If you want to develop your English deep, you should not stuck at graded books because they can limit you. As soon as you can freely read advanced level books you should move on. But if English is just your hobby you can just enjoy reading graded books.

Site functionality

A: Now Read-online feature is available only for authenticated users. This means that you should Sing-up (register) and log-in at site. When you do so - Read Online button will be shown at every book page.
A: It's true, sorry for inconvenience, we are working on new level-calculation algorithm and soon levels of the all books will be re-calculated.
A: Direct download means that zip-archive with mp3 files would be downloaded directly for the server english-e-reader.net. Currently this download is fastest and easiest. Unfortunately it's impossible to store all audiobooks at this server because audio files are too heavy. Mirror download means that the same archive would be downloaded from another server, but sometimes it could be unavailable. Torrent file uses peer-to-peer network that means that people who are downloading or already downloaded files are sharing them without other people who want to download the files. This way of downloading potentially has the maximum speed and also stability - because no server required for downloading. But it has some disadvantages too - you need to install additional software called torrent-client (e.g. qbitorrent or utorrent). Also at some countries torrents are not allowed by law.