anime plot questions - ep. 12 + 13

1. Episode 12 - what was the reason that Chise lost her voice?

1.5. Episode 12 - When Shuji was reading the diary, Chise was sitting on the roof, what's the difference between this Chise and the one before? Was she like a complete robot Chise that the military from scratch with little of Chise's memory or something? And what happened to the Chise before?

2. Episode 13 - So confusing, we see that Shuji is with Chise, then she had to go fight, and then there is a tsunami, then Shuji is in this "white dust world" and at the very end they are dating. Can somebody give me a thorough plot of episode 12, like what is this "white dust world" and what happened to Shuji afterwards, and the dating in the end is it they gone to the past/started over or is it just in Shuji's memory?

2.5. Episode 13 - when the war started, what are those grey looking spikes in the red sky?


For all my anime questions I usually go to Yahoo Answers, but seeing that people are still here, I thought asking here too.