The quality control on which is myth and which is debatable and which may have a lot of truth to it isn't very good here. Dismantling the ones that are actually myths is very important, but having a dialog about ones that are not myths is also quite important if anything is going to happen besides the raw exertion of power by both sides with the actual needs of trans people taking a backseat to posturing.
First, there's a zeroth myth that I really think is worth bringing up: being trans is not (always) a choice, it's how people are. While there may be some people with minimal gender identity or whose gender fluidity would allow them to take a traditional or a non-traditional role at their discretion, this is not the norm, and it certainly isn't the only way it happens. The myth that it's an ideology, not a state of being; that you could turn it on and off like deciding to say "please" and "thank you" or instead be rude; is one of the most pernicious because it makes identity look like a narcissistic display of rejection of society.
(1) Yes, trans identities are historically documented. You nailed this one.
(2) The problem with "is unnatural" isn't that it's a myth. The problem is that it doesn't even have an objective truth value. Cancer is natural, in a sense. Doesn't make it good. In another sense, though, as cancer is misregulation, is unnatural--it's not how things are "supposed" to work. This isn't a good candidate for debunking as a myth by pointing out that gender change happens in nature. You just need to reject the premise.
(3) Whether or not trans people are mentally ill is, again, a bit difficult to determine objectively. At some times, mental health experts have said yes. At other times, no. It's kind of society's call to determine what "ill" means. Certainly people with gender dysphoria have distress, and certainly if there were a drug that eliminated dysphoria, that source of distress would vanish. But there isn't such a drug. So care that reduces distress typically involves facilitating a better match between felt gender (which we don't know how to manipulate) and presenting gender (which we can do something about). And, often, it helps people! That's great! The discussion about "mentally ill" isn't so much a myth as a red herring. If trans people are the way they are, and we're going to help them have better lives, then we help them regardless of whether we label the unhelped state (or the helped state) "ill". (Trans people may find certain labels rude or demeaning, but that doesn't make it a myth, just impolite, if you use the wrong characterization. Again, illness as opposed to difference-that-needs-attention is socially constructed. It's not really a matter of objective truth.)
(4) The ease of getting gender affirming care is a myth and it is perpetuated extremely strongly by trans advocates. This one is really bizarre. When people who think it's easy say, "We should add more checks!" (e.g. gender recognition certificates in Scotland, or getting gender-affirming care without parental knowledge at 16 in some state(s?) in the U.S.) instead of the trans advocates going, "No we don't need more, we have LOTS already! Look!", they instead go, "Fewer or none! Fewer or none!" Leaning into this one would easily eliminate the myth.
(5) It's absolutely true that transitions can't be forced under any normal circumstances--anything to the contrary is a myth. People are weird and horrible and manipulative, so you should probably never say never, but this kind of thing would be an extremely rare and shocking outlier.
(6) Whether or not the risks of gender-affirming care warrant a ban, especially for some presentations or some age groups, is a matter for societal debate. If you feel very strongly about the Hippocratic Oath ("do no harm"), there is in fact a very good case to be made that we don't have an adequate handle on limiting potential harm. On the other hand, if you take a more utilitarian perspective--maximize good overall, recognizing that some people will be harmed but that it's worth it when far more will be helped--you might come to a very different conclusion. This is something to debate out. There's no uniform conclusion in general, though it's worth noting that the take-risks cases that you've presented are all in cases where the alternative is near-certain death. Very rarely is that true for gender dysphoria. Anyway, this is certainly not in myth territory, unless the statement is taken to only be that the very most extreme version is a myth (i.e. nobody of any age ever should get any gender-affirming care under any circumstances) and slightly milder versions are topics for debate.
(7) You've responded to a myth with something that...may well be a myth. The methodology of the study you refer to is badly flawed for answering this question because it asked trans people about detransitioning. No effort was made to seek out people who had detransitioned and no longer identified as trans--the whole point of the survey was to find out about trans people, so the methods were designed to get as broad a reach within the trans community as possible. That's awesome for answering many questions about the trans experience, but not this question. In contrast, a study selecting specifically for people who identified as having detransitioned gave quite different answers. Anyway, if everyone detransitioned and regretted the transition, that would be very clear evidence that gender-affirming care should be banned. But that is absolutely assuredly not anywhere near reality. So yes, the myth you state is totally a myth. You just have a more-myth-than-proven response.
(8) As things stand, trans people are not a threat to public safety--that is absolutely a myth. You respond, however, with a non-sequitur, saying that trans people are under threat. This is true, well-documented, very serious, and irrelevant to the "myth". You can be under threat and still be a threat. More to the point, most of the anxiety comes up not with existing situations but the ideal as proposed by trans advocates. We don't know enough to state with confidence which of those measures might have risks associated with them. For instance, even something as basic as the social-and-socioeconomic-situation-adjusted propensity to violence for cis women vs trans women isn't very well documented, let alone anything more complicated like how or whether this might change with different types and durations of gender-affirming care. So it's a myth that trans people are a known threat to public safety. It is also a myth that proposed changes are known not to have any risk to public safety. The whole discussion needs to be more mature and evidence-based...or even happen. The literature is very scant in this area.
(9) This is provisionally a myth, given how completely medically deaf anti-trans bills have tended to be at least in the states in the United States that have passed them. However, there is a poorly-understood phenomenon that adolescents are identifying as trans at something like triple the rate of other groups. That's...odd. Futhermore, the Amsterdam gender identity clinic has quadrupled its rate of proceeding without hormone therapy or surgery for people who come to them. This gets back to point (4): if the safeguards are extensive, the risk is very low. But given the changing demographics--and, ironically, the increasing acceptance of trans identity in some circles lessening the overwhelming (and perhaps at times excessive) pressure to come up with really clear diagnoses--I don't think we can put this on a shelf and say, "Myth, forever and always." It needs constant revisiting. The existing bills are really, really bad, though.