That seems to have more to do with his refusal to face the music on rape charges than his releases.
> while hearing via media politicians (mostly Democrats) calling for his death
For most of the time since WikiLeaks involvement in the publishing the Manning docs, the calls for his punishment, including by the most drastic means, have been bipartisan but stronger on the Republican side. The Republicans changed their tune after Assange participated in the release of the DNC hack recently, but its somewhat revisionist to pretend that history started just a few weeks ago.
She declined to do it anywhere but Sweden if my memory serves.
Politicians calling for his death is just grandstanding. In fact, the possibility of the death penalty is probably the only thing that would keep Sweden from extraditing him.
The U.S. and the U.K. also have an extradition treaty, so the existence of a U.S.-Sweden extradition treaty doesn't really do much to enhance the plausibility of a double-extradition plot where Sweden extradites him from the U.K. on rape charges only as a ruse to get him into Sweden where he can be extradited to the U.S. on some other charges. (If the U.K. was a country that had no extradition treaty with the U.S. and was particularly resistant to U.S. extradition, then a double-extradition plot might be plausible.)
Now the U.S. and Ecuador also have a treaty but I don't read lawyer well enough, especially not old-timey lawyer, to know whether it would apply to anything Assange might be charged with. It does say it "shall not be applicable to crimes or offences of a political character" and I'm sure that's how Assange would characterize it (and I think that's at least partially why Ecuador has been housing him).
But the U.S. hasn't charged him with anything so there's nothing for Ecuador to extradite him for yet. In any case, the claim is a nice excuse to avoid jail in Sweden.
No, he isn't. Contrary to the ever-lasting myth, embassies have no extraterritorial status whatsoever. They are in and are a part of the host country.
But they have special protections under the Vienna Convention.
I don't know about his other leaks but there's evidence that he communicated with, arguably collaborated with and advised, Manning before Manning copied the classified material. If Manning just sent the material to Wikileaks, Assange would be in the clear (e.g. the Pentagon Papers, Trump's 1995 tax return info this week). Maybe it's not a solid enough case to be sure of a conviction, I doubt the U.S. would want to take a chance on it, but it's not like there's nothing there.
No one has suggested charging him with treason. He certainly can be guilty of espionage against the US without being a citizen.
(And his citizenship is irrelevant to whether he can exceed the protection of the 1st Amendment, since that applies whether or not he is a citizen with regard to government action such as prosecution for espionage.)
Assange surely is a conspiracy theorist to hide in the embassy when politicians publicly call for his death and his main informant Manning was placed into 24/7 solitary confinement which could only be described as torture.
> the calls for his punishment, including by the most drastic means, have been bipartisan but stronger on the Republican side
Okay, then please name a Republican that has called for killing Assange.
Sara Palin called Assange an "anti-American operative with blood on his hands" who should "pursued with the same urgency we pursue al-Qaeda and Taliban leaders".
Rep. Peter King (R-NY) called for Assange to be tried for espionage and for WikiLeaks to be designated, treated, and combatted as a terrorist organization.
Sen. Mitch McConnell (R-KY) described Assange as a "high-tech terrorist"
Newt Gingrich declared that "Julian Assange is engaged in warfare. [...] And Julian Assange is engaged in terrorism." and that "He should be treated as an enemy combatant and WikiLeaks should be closed down permanently and decisively."
Didn't he already do this? And not just once, but many times. In fact his releases have been so controversial that he has the "privilege" to live in an embassy while hearing via media politicians (mostly Democrats) calling for his death or even "droning" him. (Hillary suggested that)
Could it be that you are just a Hillary supporter that is afraid he could release something damaging about her?