Citizenship and postal address are irrelevant. If you break the law in another country and there is an extradition treaty then you will face the consequences.
Clearly I was gay while doing stuff online on a Saudi Arabian server.
Extradition is covered by a patchwork of treaties and laws most of which involve some kind of human judgement as well.
One core concept of extradition is the crime has to be, at least in broad strokes, illegal in both jurisdictions.
The crime in question also has to have some reasonable argument of jurisdiction for the requesting state. You might have been gay while buying things from an SA company, but you weren't doing anything in an interaction with SA that had anything to do with being gay. (The first dual criminality concept protects you way before having to think about this). It is also often the case that countries are reluctant or outright refuse to extradite their own citizens and choose to try them in court locally.
Assange wouldn't be protected by either of these. Conspiring to take classified military secrets with a member of the military in question would be illegal everywhere. As would participating in the taking and the following distribution.
The legal questions for Assange are "did he do those things, guiding, requesting, and helping Manning acquire and send the classified information?" "Do the first amendment protections of free speech and free press cover WikiLeaks model?" and "Would Assange receive a fair trial and just punishment if extradited?"
But in general, questions of jurisdiction are complicated. They're settled by courts, not by what people say on the internet.
Assange isn’t being accused of things that are criminal in the UK.
Whether or not the requirement is met in Assange's case is to be decided by the court. There are certainly laws in the UK that prohibit hacking. Anyway, you are wrong in general about how extradition works. People are often, for example, extradited on murder charges.
While there are certainly laws in UK that prohibit hacking (which should be abolished) they are clearly not enough to perform an extradition.
If you actually read the article on the McKinnon case, you'll see that extradition was ultimately refused by the home secretary - not the courts - on largely compassionate grounds:
"Mr McKinnon is accused of serious crimes. But there is also no doubt that he is seriously ill [...] He has Asperger's syndrome, and suffers from depressive illness. Mr McKinnon's extradition would give rise to such a high risk of him ending his life that a decision to extradite would be incompatible with Mr McKinnon's human rights."
Oddly, being gay is a crime in Saudi Arabia, but only committing homosexual acts is a capital offense. I would make a joke about the type of kangaroo court that would convict me of being gay, but it’s sad because they exist and people are convicted.
> The Justice Minister has, however, told the Dáil that he won’t extradite anyone who may be put to death for their crime.
More generally, you're at risk of extradition if the alleged crime is also a crime in the country you reside in [2].
The key with extradition is that it has more to do with diplomacy, geopolitics, and sovereignty than anything else.
Probably not, because that's not within the scope of what Ireland would be willing to extradite for.
But that's a question of Saudi Arabia’s practical ability to bring you to trial, not one of whether or not any law they have would apply to you on principle.
That's not how laws work. Laws are limited in territorial applicability only to the extent that the sovereign adopting them so limit them, and basically no government would fail to hold foreign coconspirators in a crime occuring within their domestic jurisdiction immune to prosecution (some might not have the practical means to bring such an actor to justice, and some might not choose to apply them in most cases as a matter of policy priorities, but that's a different issue.)
Aiding and abetting.