Does locking doors generally lead to preventing break-ins? I mean, certianly in some cases (cars most notably) it does, but in general, if someone has gone up to your back door with the intent to break in, how likely are they to give up and leave upon finding it locked?

Nitpicking is absolutely critical in any public forum. Maybe in private, with only people who you know well and have very strong reason to believe are very much more likely to misspeak than to misunderstand, nitpicking can be overlooked. Certainly, I don't nitpick every misspoken statement in private. But when those conditions do not hold, when someone is speaking on a subject I am not certain they know well, or when I do not trust that everyone in the audience is going to correctly parse the statement as misspoken and then correctly reinterpret the correct version, nitpicking is the only way to ensure that everyone involved hears the correct message.

Charitably I'll guess that you dislike nitpicking because you already knew all those minor points, they were obvious to anyone reading after all, and they don't have any major impact on the post as a whole. The problem with that is that not everyone who reads Less Wrong has a fully correct understanding of everything that goes into every post. They don't spot the small mistakes, whether those be inconsequential math errors or a misapplication of some minor rule or whatever. And the problem is that just because the error was small in this particular context, it may be a large error in another context. If you mess up your math when doing Bayes' Theorem, you may thoroughly confuse someone who is weak at math and trying to follow how it is applied in real life. In the particular context of this post, getting the direction of a piece of evidence wrong is inconsequential if the magnitude of that evidence is tiny. But if you are making a systematic error which causes you to get the direction of certain types of evidence, which are usually small in magnitude, wrong, then you will eventually make a large error. And unless you are allowed to call out errors dealing with small magnitude pieces of evidence, you won't ever discover it.

I'd also like to say that just because a piece of evidence is "barely worth mentioning" when listing out evidence for and against a claim, does not mean that that evidence should be immediately thrown aside when found. The rules which govern evidence strong enough to convince me that 2+2=3 are the same rules that govern the evidence gained from the fact that when I drop an apple, it falls. You can't just pretend the rules stop applying and expect to come out ok in every situation. In part you can gain practice from applying the rules to those situations, and in part it's important to remember that they do still apply, even if in the end you decide that their outcome is inconsequential.

While you can be definitively wrong, you cannot be definitely right.

Not true. Trivially, if A is definitively wrong, then ~A is definitively right. Popperian falsification is trumped by Bayes' Theorem.

Note: This means that you cannot be definitively wrong, not that you can be definitively right.

They should be very, very slightly less visible (they will have slightly fewer resources to use due to expending some on keeping their parent species happy, and FAI is more likely to have a utility function that intentionally keeps itself invisible to intelligent life than UFAI, even though that probability is still very small), but this difference is negligible. Their apparent absence is not significantly more remarkable, in comparison to the total remarkability of the absence of any form of highly intelligent extra-terrestrial life.

Alternatively, if you define solution such that any two given solutions are equally acceptable with respect to the original problem.

WOW. I predicted that I would have a high tolerance for variance, given that I was relatively unfazed by things that I understand most people would be extremely distressed by (failing out of college and getting fired). I was mostly right in that I'm not feeling stress, exactly, but what I did not predict was a literal physical feeling of sickness after losing around $20 to a series of bad plays (and one really bad beat, although I definitely felt less bad about that one after realizing that I really did play the hand correctly). It wasn't even originally money from my wallet; it came from one of the free offers linked elsewhere in this thread. But, wow, this advice is really really good. I can only imagine what it's like with even worse variance or for someone more inclined to stress about this sort of thing.

If I can do something fun, from my house, on my own hours, without any long-term commitment, and make as much money as a decent paying job, then that sounds incredible. Even if it turns out I can't play at high levels, I don't mind playing poker for hours a day and making a modest living from it. I don't really need much more than basic rent/food/utilities in any case.

You see an animal at a distance. It looks like a duck, walks like a duck, and quacks like a duck. You start to get offended by the duck. Then, you get closer and realize the duck was a platypus and not a duck at all. At this point, you realize that you were wrong, in a point of fact, to be offended. You can't claim that anything that looks like a duck, but which later turns out not to be, is offensive. If it later turns out not to be a duck then it was never a duck, and if you haven't been able to tell for sure yet (but will be able to in the future) then you need to suspend judgement until you can. Particularly since there is no possible defense that the thing is not a duck except to show you that it is not a duck, which will happen in time.