The language is, of course, English.
By revision, do you mean the version of Kindle firmware? It's 5.0.3. I don't know why, but my Kindle doesn't accept any updates even though I downloaded the proper firmware from Amazon and followed every single path they've stated. It shows various update screens, but Device Info of Settings menu always display the version of 5.0.3.
I'm kinda frustrated as this is the first time for me using any kind of E-ink reader.