1. There indeed wasn't much evidence for it, but that's not necessarily something that would immediately make such claims conspiracy theories given it's entirely plausible if you just look at the pieces in play here (lab + crowded urban center = potential no bueno grande [I don't speak Spanish, incidentally]). A fine line, to be sure, but one I think can be clearly drawn.
2. Agreed. To any reasonable person, it is evident China has no reason to launch a bio-attack on the planet at large. The evidence against such a move, both in practice and in light of their global strategy to this point, is overwhelming and irrefutable. It wouldn't be something I'd rule out if this came from say, North Korea, Iran, or other similar state, but that didn't happen and will be relegated to the historical hypothetical dustbin.
3. Willful idiots strike again. I personally didn't change up my routine much once lockdown ended, but I've always been pretty conscientious regarding personal and public hygiene, so other than wearing a mask where people asked me to there wasn't much to change...for your average, "I cough on my hand, adjust my contact lid with that hand, and then shake yours." person though it certainly was downplayed to a degree totally inconsistent with the alleged bio-attack mania.
4. Willful idiots strike yet again...smh
As you note, it did function as a serious distraction from actual measures taken domestically, and we saw serious failures (as well as chalked up notable successes) at ALL levels (Federal, State, and Local).
In the end, I regard it as one of those situations where you hate the speech being thrown around, but it's still free speech. Best thing we can do to combat it is drown them out with actual facts, realistic strategy, and in general exercise our free speech louder than they do theirs. Private platforms can do as they will, of course.