As I pondered all of the proposed additions, it occurred to me it was becoming like a test question. "In two paragraphs define the history of religious thought- be thorough but concise." LOL
To add something like a concordance without too huge enough effort, the index function of a word processor might do some good. Good for words, but not so good for ideas.
What is really needed is some of tools available to download on line, and a two monitor set up to keep from going back and forth, back and forth.
E-sword has a number of those tools.(
www.e-sword.net) But they are integrated with his software. His KJV has the Strong numbers added.---(He thinks: great I get to start all over!!!)
I think the commentaries are a great idea if possible. So many times when I am reading the Bible it seems like there are so many things that were common knowledge to the people of the time that we don't share the same perspective. There are very few people in Europe and the US that are subsistence farmers as were nearly all the early readers of the Bible. It is so agricultural that it is hard to really get the point sometimes. The commentaries would help bridge the gap.