Regarding how the debate went in Sweden, it was raised that Assange could be snatched up en route from UK to Sweden. This notion was dismissed even more summarily, like some spy movie fantasy.
(This would not happen unless the UK would be OK with it, of course. The UK, unless they have some exceptional reason, does exactly what the US says. If the law has wiggle room, they'll look the other way. I am sure also something could be arranged so Sweden and the UK could save face for each other in their relationship.
Even if the US black bagged someone, as long as they didn't do it on UK soil, why should the brits just not shrug and say "ah, those naughty Americans, can't keep up with them all the time eh?" wink, wink, nudge nudge)
Edit:
Regarding the charges themselves against Assange - I have no doubt Assange is a bit of a douche. I would not be surprised at all if he violated Swedish law. It's still quite suspicious that even though most similar investigations are closed, even with better evidence, this case was opened anew, by Marianne Ny. Of course the handling of this case was political.