"I really want to understand why I need EF at the most basic levels"
Entity Framework just simplifies your day to day data access. Instead of thinking how to create a data access layer our spending time writing raw SQL queries, EF can just do it. Is it the 100% solution for your projects, no, but it will sure get you closer faster than trying to write things by hand.
In response to your questions about books, Lerman's books are probably the best in showing Entity Framework working in a number of different scenarios. The book that Chad referenced is also another good resource. But I'd also recommend taking a look at the ADO.Net Team Blog and read some of their entries on Entity Framework, along with the Entity Framework Blogand using the Data Developer Center to get a good understanding of when, how and why to use Entity Framework.
Nice to see that you're diving into Entity Framework and hope it helps you out in your projects.