1. The dictionary is builtin. You do NOT have to be connected to use it. Only wrinkle - there is no facility to key in a word and look it up - i.e. the word must be in the book you are reading; you then select it and click "Look up"
2. You can turn WiFi off. In fact, with the STR I seldom if ever turn it on, usually only if I want to buy a book. This is completely opposite from the way I use my Color Nook (a tablet), where I usually have WiFi on, because I am picking up email, surfing the web, etc
3. No, side-loaded books can only be deleted by using the USB connection and a computer.
4. You can sort books either by title or author. If you sort by author, it uses the last name of the author.