1) Dirty Secret - Many students don't do all the reading. That being said, the more reading you do, the better your in class experience will be.
2) What's not clear on that website is that you don't read the entirety of some of those books (Herdotus, Thucydides, The Bible (you only read Genesis, Job, Luke, and John) in the fall)
3) Hanajima, that's not entirely true. Every section of lit hum is required to read a certain set of books, with the option to add a few short readings, or use that time to catch up on the required selections. The curriculum is *relatively* stable and uniform. Comparing my bookshelf (I took Lit Hum 5 years ago... yikes) to the reading list, none of my books have been removed, and Gilgamesh, Ovid, Purgatorio, and Paradisio have been added.
4) You might find this:
Literature Humanities - WikiCU, the Columbia University wiki encyclopedia and this:
Books about Columbia - WikiCU, the Columbia University wiki encyclopedia interesting.