Arcanletia, Crimson Village and other locations are planned locations for future chapters and as such will always be available in Public Releases. We've still got some content to work through in Chapter 1 though :)
Cockatrice can't be fought yet, that encounter will mark the end of Chapter 1. Megumin's and Rem's panties are the only ones you can Steal (aside from Chris's, but those are plot-related)
Hi! Since the game is still in active development and I often go back to rewrite/fix some parts, I'm not planning on adding an official translation just yet. Potentially after Chapter 1 is complete.
That said, there's a lot of text in the game, which would be a lot of work to take on