The key is being able to mod the AI as you hinted in Item 6 (also exploration AI, fleet building AI and so on). Technology selling is also a huge exploit that has never been fixed. The other items would slow it all down but it's easy enough to win on Extreme even when other empires are far more advanced as well (or die in 5 minutes, nothing in between).
Yeah, I know about tech selling but there's no fixing the values of tech and I don't think mods can convince the AI that paying 100k credits for a tech that's "worth" 200k is actually a bad deal. Then again, I'm not sure how the mechanoids are made to refuse any and all trade, but some level of that might work as a fix for those who don't want to disable tech trade entirely.
And yes, the other things won't keep you from winning but they'll even things out a bit. And alleviate the pain of either being tremendously inefficient or being stuck in a micro nightmare. It's also my suspicion that the AI ends up building itself into a corner somewhat by trying to build too much and then running into corruption issues that reduce further economic growth.
But what you seem to be hoping for, I gather, is something that will make the AI a better "chess player" than you are and that's just not likely to happen in a game this complex. There will always be moves and counter-moves and since you're human, you'll be actively looking for AI behavior patterns and how to manipulate them while the AI can only really be programmed to look at the raw basics of the scenario and how to respond to that. This means you can set traps for the AI but it can't very easily set traps for you.
What can happen, however, is that the AI empires are made sufficiently competitive that you have to worry a whole lot about getting yourself entangled in too many confrontations. Think of it as a tiger vs wolfpack scenario. A tiger will kill a wolf any day, but a tiger can only chew on one thing at a time. If you're busy chewing on one wolf then the other 12 might decide to start chewing on you. If you refrain from chewing on anything then they'll back off, but then you'll also not be able to eat.
There's one other thing I don't know how to fix, by the way, and it involves the rather predictable AI response whenever hostile ships moves into a system. Abusing this won't make battles totally one-sided, but it will help reducing the effect of an AI having numerical superiority in the system, assuming tech parity. Fixing this means messing with the raw AI code, which almost certainly won't be an option.
Oh, and of course there's the obvious diplomacy thing where you bend over backwards to keep the other factions happy while you maul convenient targets one at a time, keeping you out of multi-front wars. That's not something a modder can fix either. I think the best answer for this is a historical aggression value assigned to each faction, so if someone decides to pull a Putin then other factions will remember it and be paranoid as hell about it for a few decades, no matter how much one tries to chat them up.