Why the rush to judgement and such a williness to assume guilt. I will say there is a possibility he is guilty. But, his crime I don't think warrants an international incident if it is as described.

It seems to me that, by ignoring that bit, it is you who is indulging in selective quotation by just stating 'Mr Assange has not committed a "serious non-political crime"', and 'this is not a serious crime'. They do, however, have the serious reasons for considering that he did. Ecuador says that, without their concern that the USA will try to extradite him from Sweden, they would want him to return to Sweden for the questioning. This rather shoots down the idea that there is a problem with the arrest warrant. Ecuador has decided to put his fear of US extradition above the normal extradition process, and The Guardian is pointing out that this decision goes against the UN convention.

The Swedish government cannot undertake to never render him to the USA. That would (a) be political interference in the judicial process (b) be a promise to ignore any future evidence given to Sweden.

Your point about questioning outside Sweden does have some merit. I believe that the case Sweden puts forward is along the lines of that if, at the interview, he refuses to answer some questions, they would have the right, in Sweden, to put him in custody as not co-operating, and to proceed with charges, while they wouldn't be able to do that outside the country.

The chance of Assange getting a fair trial in Sweden is long past. That went away when the original prosecutor - very unlawfully - confirmed suspects name to media. And now as the case is very public, all the Swedish opinions hostile to Assange that the OP keeps spreading just confirm that fair trial would be impossible. Secrecy in rape cases is there for a reason, to protect both victims and the suspect.

CONVENTION AGAINST TORTURE and Other Cruel, Inhuman or Degrading Treatment or Punishment
http://www.hrweb.org/legal/cat.html

Article 3

No State Party shall expel, return ("refouler&quot or extradite a person to another State where there are substantial grounds for believing that he would be in danger of being subjected to torture.
For the purpose of determining whether there are such grounds, the competent authorities shall take into account all relevant considerations including, where applicable, the existence in the State concerned of a consistent pattern of gross, flagrant or mass violations of human rights.

If Assange is extradited to the US, he'll be subjected to torture.

In fact, it's almost certainly wrong. When has Obama had someone tortured?

No, Amnesty did not call the treatment of Manning 'torture'. It was also in military detention, which would not be where Assange would be held.

Daniel Ellsberg: I Congratulate Ecuador for Standing Up to British Empire to Protect Julian Assange
http://www.democracynow.org/2012/8/17/daniel_ellsberg_i_congratulate_ecuador_for#transcript

So I think that—in fact, I join his lawyers, Michael Ratner and others, in saying that he has every reason to be wary that the real intent here is to whisk him away to America, where it really hasn’t been made as clear what might be waiting for him as I think one can conjecture. The new National Defense Authorization Act—and I’m a plaintiff in a suit to call that act unconstitutional, in terms of its effect on me and on others, a suit that has been successful so far at the district court level and has led to that act being called unconstitutional. But on its face, that act could be used against Julian Assange or Bradley Manning, if he weren’t already in military custody. Julian Assange, although a civilian, and not an American civilian at that, would seem to me, a layman, to be clearly subject to the National Defense Authorization Act, the NDAA, putting in military detention for suspicion of giving aid to an enemy, which he’s certainly been accused of by high American officials. I don’t see why he couldn’t be put in indefinite contention, without even the charges that I faced 40 years ago for doing the exact same things that he did.

...

Keep parsing.

From Amnesty International:
http://www.amnesty.org/en/library/asset/AMR51/006/2011/en/df463159-5ba2-416a-8b98-d52df0dc817a/amr510062011en.pdf

The conditions under which PFC Manning is held appear to breach the USA’s obligations under international standards and treaties, including Article 10 of the International Covenant on Civil and Political Rights (ICCPR) which the USA ratified in 1992 and which states that “all persons deprived of their liberty shall be treated with humanity and with respect for the inherent dignity of the human person”. The UN Human Rights Committee, the ICCPR monitoring body, has noted in its General Comment on Article 10 that persons deprived of their liberty may not be “subjected to any hardship or constraint other than that resulting from the deprivation of liberty; respect for the dignity of such persons must be guaranteed under the same conditions as for that of free persons ...”.

The harsh conditions imposed on PFC Manning also undermine the principle of the presumption of innocence, which should be taken into account in the treatment of any person under arrest or awaiting trial. We are concerned that the effects of isolation and prolonged cellular confinement – which evidence suggests can cause psychological impairment, including depression, anxiety and loss of concentration – may, further, undermine his ability to assist in his defence and thus his right to a fair trial.

...

All Assange, all the time.