If he's so unimportant, why does the U.S. ambassador to Australia negotiate the terms of an extradition - just in case?
That was pure speculation on Australian diplomats' part.
If he's so unimportant, why insists Sweden on a witness statement given on swedish soil? (Yes, the extradition request is for a witness! It's not as if the state attorney already has filed charges.)
In Sweden, it is about setting an example. Sweden is the Saudi Arabia of feminism. Sweden has the highest number of rape cases per capita of any country in Europe. And not just by a small margin, twice as many as the country in second place, the UK.
Getting Assange to Sweden to be questioned and perhaps convicted of a rape would set a great example, not just at home, but abroad, considering the international fame of Assange. At least, that is the thought of the Swedish prosecutors.
If he's so unimportant, why does the UK government threats to storm the Ecuadorian embassy over him?
Because it's Ecuador; who gives a shit? The UK has had this law for a while now, and all embassies in London should be quite aware of it. I sincerely doubt other nations will 'pull their business' if the UK storms the Ecuadorian embassy.
Ecuador is using the situation to make a stand off against the USA, the UK and Sweden, because of its own demented obsession with its Anti-American sentiment. I don't know if Ecuador honestly believes he won't receive a fair trial in Sweden, but that doesn't really matter, because Ecuador can 'make a stand' against the USA.
I could also ask you a counter-question: Why is he not getting extradited from the UK? Sweden - unlike the UK - has never been an ally of the USA. Not that they are enemies, but they are not active allies. Sweden is far too liberal to be thinking about extraditing Assange to the USA.
And one more question: What laws can the USA extradite Assange for? Assange hasn't broken any American laws. And even if they could, those laws would likely fall under military or political prosecution, two areas Sweden will not extradite people under.