The "several additional books" are the Epistle of Barnabas and the Shepherd of Hermas, which weren't unanimously dropped from the canon until a few decades after Sinaiticus.

Codex Sinaiticus is one of the main sources for all of the modern translations. The only thing new about this is that hi-res photos are available via the web, instead of the 100 year old black and white facsimile that everyone was forced to rely on all these years. You can get that by googling codex sinaiticus pdf. But you'll need to know Koine Greek, a bit of an effort for your average lazy skeptic.

..."enlightenment's" offspring, corresponding to the totalitarian communism and fascism produced by the original "enlightenment?"