Do you have a laptop? For textbooks, I think that a laptop is much better than a dedicated e-reader. You will flip around a lot more in most textbooks than you ever will in a novel, and that is easier to accomplish with a laptop. All of the e-reader formats have free apps for your computer, and a basic laptop isn't any more expensive than an iPad or Kindle DX.

The first semester you try e-books, just do one or two. I found that I prefer paper textbooks to e-books. Many of my classmates seem to get along OK with e-books. It's an individual thing.

Open book tests are definitely a problem. In a small class you might be able to work out something with the professor (I was able to do this in a class of 14 students) but it's definitely up to the professor.

Another problem with electronic textbooks is that they don't always have page numbers. Some of my professors assign reading by the page numbers. Page numbers are also an issue when it comes to academic citations.