I'm not talking about any really existing socialist society, only the abstract idea of socialism. There doesn't need to have ever been or even ever be in the future of humanity a really existing socialist society for the potential of socialism to exist. And note I didn't say property would be abolished in a socialist society, only that theft would be redefined. That implies property would continue to exist -- but rather than being owned by private individuals, it would be owned by the state or by collectives, unions, etc.
While I understand an abstract ideal, it can't survive if it doesn't match up with reality which I think I will elaborate further down
A society in which property is abolished is a communist society, one of whose conditions is post-scarcity, but in a post-scarcity society the concepts of theft and property themselves become moot. And again, I'm not talking about whether or not a post-scarcity society can really exist, only saying that it can potentially and in theory, and as such I don't believe property is a product of human nature as much as it is of economic conditions.
This is where I diverge. I state that humans seem to have an innate desire for private property, not based on an economic model but based on a sociological model that every human being, while wanting to be a part of a collective also wants to be separate, individual, and unique. While there may always be a "we" that we want to belong to, there is always an "I" as well. This extends from ourselves to things we see as an extension of ourselves. Things that we attach a sentimental value to for whatever reason, be it a logical conclusion that one's work is unique or a purely sentimental attachment to place or thing there exists the "I" and "mine" in almost all but the fantastically impossible situations. In that sense, private property is no more "abolish-able" in theory than in practice.
Also, no, I don't believe anything is inherently and intrinsically immoral. Morality is an emergent factor arising from social interactions, there's nothing anyone can do living alone that can be immoral, because s/he would not be interacting with anyone. And even given social interactions, morality is relative to a society. You could say that what is best for the majority of people is what's moral, but that itself is a liberal notion of morality that assumes too much -- there's nothing inherent about that definition of morality. Not to say that I'm a moral relativist, but I give morality my own definition and recognize that it is my own.
Perhaps, but even in a relativistic atmosphere there are underlining principles at work. If we agree that each individual creates his/ her own morality then no one person's or groups of people's morality is superior in the sense of enforcing its morality on the other. In that sense, the non aggression principle is born. The common dissent is the classic " Sez who?", but the underlying principles deduced show that it isn't a matter of "Sez who?" but the very idea that we don't know lends to the "supremacy" of the individual and their give and take with other individuals. Only through persuasion and voluntary conversion should morality be established. In that sense, stealing to live isn't a intrinsically moral thing to do, but though human interaction and persuasion and empathy we see that we are persuaded that it is the correct thing to do, and those who disagree will be social shunned by those who do agree. We know that living is preferable to not living and that if another person lives and costs me trivially then the proportion of rights ( as persuasively argued, not intrinsically enforced) is to the person who lives and not the person who misses out on an extra 8 inches on his/her TV.