I am the Kat that Walks By Itself

I waited to answer this, as I knew we were due to see Dalek again today in the BBC3 reruns.

I see no reason to doubt the Dalek's statement that it's a soldier bred to receive orders, but its position is unique and I think it's capable of adapting. Even before its encounter with Rose, it seems to be emotionally savvy; it understands exactly how to needle the Doctor, and later how to manipulate Rose into touching it. Maybe half a century in captivity on Earth has given it some sort of insight into human behaviour, even if it's been the brutal end of human behaviour.

And then there's the transformation effected through Rose... I still have difficulty swallowing the explanation, but if we're to accept that it absorbs emotion through Rose, I don't see why it shouldn't absorb something of her independent spirit. Plus it's downloaded the internet and "knows everything".

And it's just learned through the Doctor that it is the sole survivor of its race, so if it does survive its apparent suicide it may feel it is the Emperor by default, and has a duty to recreate the Daleks from scratch, even if it takes 20,000 years. (To answer your question, if the Emperor is a completely different Dalek, I don't think it's lurking around Earth undetected in 2012, I think it arrives later.)

I don't think we have to accept that the van Statten Dalek is redeemed by Rose, or has any real chance of coming to terms with its human emotions. It explicitly rejects its mutation - "I shall not be like you!" - and then there's the bizarre command to Rose: "Order my destruction! Obey! Obey!" It has already moved from awaiting orders to giving them, even if they are, paradoxically, a final attempt to get someone else to take charge.

Maybe it really does commit suicide. Or maybe it intends to, and survives through a freak accident. If so, it has 20,000 years to think about its purpose, plan its strategy, and start to carry it out. (And I'm not clear how long a Dalek can live; if its lifespan is limited, it's possible that the Emperor who challenges the Doctor is a "descendant", in the sense of one in a line created by the van Statten Dalek, and gradually bred to adopt an imperial stance.)

I'm not sure that the van Statten Dalek wouldn't fear the Doctor, especially when he's boasted to it that he destroyed the entire Dalek race, and then become associated, however unintentionally, with the new threat of contamination through humanity.

As you say, there are striking similarities between the vSDalek-Doctor and Emperor Dalek-Doctor exchanges - both accuse him of cowardice, and both highlight their potential likeness. And another reason why I like the van Statten-Emperor link is the same thing that you have mentioned: "the sinking feeling when we find out that the actions in "The Long Game" actually made things worse."