A lot to unpack here. I will try to respond to the questions you ask. Hopefully that will clear up some misconceptions.
You wrote: "To pass as the opposite sex from your birth sex, I’ll assert you’ll more likely than not express stereotypically feminine traits and qualities — do you find this not to be the case?"
Not really, no. It's true that most trans women go through a stage where they express themselves in a clearly feminine way. That is mostly because society tells us that in order to be considered women we need to be ultra feminine. Most of us, once we are more comfortable with our gender, tone it down to one extent or another. Although I know trans women who dress ultra-femme, I also know many who don't.
"Do you think you can pass for female without being feminine?"
Well, as I've said, I rarely wear makeup, I usually wear jeans and t-shirts, and I am usually treated as a woman. A couple weeks ago, my wife and I got out of our car at a garage in NYC. I was wearing a ratty t-shirt, shorts, and a baseball cap to contain my messy hair. The woman working the garage turned to us and said, "I assume you ladies are here to park?" So, yeah, I not only think so, I know so.
"And if you can pass for female without being feminine, can you pass for female while being masculine?"
Not sure what you mean here by being masculine. Facial hair? Muscles? If you mean something along those lines, I don't know because I don't choose to look that way. I will say there are trans women with beards and trans men without them. I know non-binary people with and without facial hair, with and without breasts, on HRT and not on HRT.
"Taken one step further, can you pass for female while being 100% physically male and masculine?"
Again, it depends on what you mean by this. Also, for many trans women, the existence of male physiology triggers dysphoria. As a result, many trans women take HRT (estrogen, in this case) and have a love-hate (mostly hate for most of us) relationship with their genitals. I think it needs to be said here that there is a huge difference between being gender identity and gender presentation. There are many trans women who still present as masculine because they have no choice; they are unable to start transition to a presentation that is more feminine, they are unable to get access to HRT (if that's what they choose), they aren't ready to transition, and many, many other possible reasons.
"I think once you argue that you can pass for female without being feminine, the logical conclusion is that “passing” isn’t a thing — do you disagree?"
I don't think "passing" is a thing, but not for the reasons you suggest. I first need to say that I am really not a big fan of the word "passing." It implies that we are trying to get away with something, trying to blend in so as to fool people. It implies deception. It also implies we are trying to get people to believe we are something we are not.
I am not a "man trying to pass as a woman" (and I'm not implying you said this; this is what many people think of when we talk about a trans woman "passing"). I am a woman with a history of being trans, and the way I look, talk, and act means that people usually treat me as a woman. It also seems that being treated as member's of your gender are typically treated is what most people mean when they say "passing." As I pointed out above, those aren't they same thing. I am not trying to get away with anything or deceive anyone; I want to be treated like other women are treated because I am a woman.
So no, to me, passing isn't a thing. It's also something that seems to get made way too big of a deal of: some trans women look more like some random ideal of what a woman is supposed to look like than others, as do cis women. There are cis women with receding hairlines and some with Adam's apples, or big hands. There are trans women who fit that random "feminine ideal" so well that they win beauty pageants.
As I said above, gender identity and gender presentation are two different things. I am a woman. That's my gender identity. But I present as what many would call a "soft butch:" my hair is just above my shoulders, I wear earrings, but usually studs. I wear jeans or shorts and t-shirts most of the time. I have not worn heels higher than half an inch since 2013.
Hope that helps.