solarpunk memes

You look for a nicer house that no-one seems to be using and ask the neighbors if it is indeed free to move in and then you just do it if no one has any serious objection.

The second question is a bit harder to answer and not directly related to personal property as a concept. First of all, when you personally no longer need the house it de-facto has no value to you any longer, hence the question is a bit moot. But of course when it is part of a relocation, where you might, or might not move, or might decide to rip out the floor that you placed in the old house to move it over to another one etc. then it is perfectly feasible that you talk with the person that has shown interest in your old house about some sort of deal that both sides benefit from. In the end you can only win in such cases, as an empty house quickly falls into disrepair and loses most value anyways. In some cases the neighbors might also chip in to compensate you instead, as they don't want an half broken house in their neighborhood. And when your house is part of a cooperative housing project, there might also be a general prior understanding between you and your co-owners that they will compensate you fairly when you leave the housing coop. So tl;dr, it depends.

Land ownership is generally not a thing... it's a logical fallacy that you can "own" land (and many countries around the world already recognize that), so at most it would be the garden around your house, or the agricultural field that you regularly plant on. If you regularly use the forest productively, you might earn certain usage rights, like the right to collect mushrooms or do sustainable logging, but that wouldn't extend to the forest itself or the land it grows on. Personal property is limited by what you can as a human realistically use in your everyday life, but of course there is also associative ownership, like being part of a worker owned company or a cooperative housing project.