Did you see these too?
This is not theoretical, this is what they have now and it works.
I don't know what performance will be like. With some luck they will talk about this in the upcoming podcast dedicated to community questions, keep an eye out for it.
I don't know. With enough players it should work out, if NQ knows what they're doing. And from what I understand they're taking inspiration (and employees) from EVE for this.
As for immersion, Noveans have all the same "funny" shapes that humans do...
But seriously, I'm not too worried about it becoming a total mess. This isn't like Second Life where you can build as much as you want out of thin air. Everything costs resources to build, and there is also the talent system which affects certain kinds of allotments and whatnot, again similarly to Eve.
I don't know what NQ's policy is on this. I doubt that they'd stop anyone from building whatever they want in the privacy of their own sanctuary, lol... But anyone who goes out of the safe zones will most likely at least fly something functional that suits their purpose. Also it seems to me that there is at least as much drive to create things that look cool or pretty or whatever, and not just "funny". If you haven't seen the twitter feed or the "community digest" posts on the news page for example, you might want to check those out.
You won't get anyone's experience so far until the NDA drops. But maybe this helps as a partial answer (albeit somewhat outdated):
If you've seen the recent roadmap update, the first version of PvP is set for the upcoming Alpha 3 phase (January 2020), and they call it one of the six pillars of the game. Nobody outside of NQ knows what it looks like yet, but clearly it will be a significant part of the overall game.
As far as I know there will not be a law system except what players and orgs make for themselves. There might be a reputation system, I don't know, I think they mentioned something about it once but nothing recent and no details that I know of. I do believe there will be a bounty system at some point, but not right away at release. There will be some safe zones, see: