Hello, friend. There are a number of misconceptions in your post, and I'd like to set the record straight a little.
Yes, there is -- we have a wonderful, robust common law system that is based in part of the concept of stare decisis. To wit, the courts base their rulings on law as it has been previously interpreted by other courts. Courts are loath to overturn existing law, since cases based on similar facts should result in similar results. Law needs to be predictable and not arbitrary. What forces Roe to stand is the weight not only of the rulings that preceded it (Griswold v. Connecticut being its most obvious antecedent), but also the cases that have followed (Planned Parenthood v. Casey, Gonzales v. Carhart, Whole Woman’s Health v. Hellerstedt, to name the biggies). Underpinning all of these rulings is (and I will expand on this below) is the concept that abortion is a legal right, with some restrictions, because it flows from the right to privacy that is provided to us all through the Bill of Rights. What forces Roe to stand up? It's a Supreme Court ruling which has not been overturned, so it is the law of this country. Which brings me to:
Yes, it is law. It is Supreme Court ruling interpreting the Constitution, as well as statutes and case law that preceded the ruling. The ruling has not been overturned. Supreme Court rulings literally are the law, because it is the job of the Supreme Court to interpret the law in a case or controversy that is brought before it, and apply it thereto. There is no higher arbiter of the law, and the rulings are law, not just "having the effect of law."
Hang tight, because I'm going to write quite a bit here. The Constitution does not explicitly mention a right to personal privacy, but such a right is implied from various aspects of the Bill of Rights. Griswold was relied on heavily by the majority in Roe in addressing the issue of privacy, so it's good to see what Griswold said. Essentially (and I admit to digging into my law school notes here), Griswold was about whether married couples had the right to use contraception. The Court held that a “right of privacy” protecting the intimate relations of married couples is implied in the Bill of Rights. For example, the First Amendment protects the right to association. The Third Amendment prohibits the quartering of soldiers in a person’s house without their consent. The Fourth Amendment protects against unreasonable searches and seizures. The Fifth Amendment protects against self-incrimination. The Ninth Amendment provides that “the enumeration in the Constitution, of certain rights, shall not be construed to deny or disparage others retained by the people.” The protected activities in each of these Amendments are “penumbras” that are not specifically enumerated in the Constitution, but instead represent various “zones of privacy” into which the government cannot intrude. The marital relationship is located within a “zone of privacy” impliedly created by these various fundamental constitutional guarantees in the Bill of Rights. Accordingly, a married couple had the right to procreate, or not, and the state could not step in and prevent access to contraception.
In Roe, the Court held that the “zone of privacy” implied in the Constitution is broad enough to encompass a woman’s right to choose to terminate her pregnancy. It went even further than Griswold, however, and said that the right to an abortion was a due process issue under the Fourteenth Amendment (with some implication of the Ninth Amendment too, reserving rights to the people). However, this holding is qualified by noting that the right is not unlimited and must be considered against important state interests in regulation. Regulation limiting a “fundamental right” of privacy must be justified by a compelling state interest, and legislative enactments must be narrowly tailored to further that interest. Applying this test to the abortion issue, a woman’s privacy interest outweighs any countervailing state interests during the first part of her pregnancy when abortion is deemed relatively safe and when the fetus is very early in its development. However, at some point in the pregnancy, the potential dangers to the mother of a later abortion and the increased development of the fetus as a potential person outweigh the right of the mother to privacy. Thus, state interests grow in substantiality as the woman approaches term and, at a certain point during pregnancy, became compelling enough to override her general right to privacy.
The concept of penumbras of the Amendments isn't some crazy idea I came up with -- in a post-Griswold universe, it's not uncommon. Penumbral rights flowing from the Amendments have been established by jurists on both ends of the political dial.
Well, yes and no. (Cf. supra on the concept of stare decisis.) It is going to take an exceedingly persuasive case, an impeccably compelling legal argument, to strip rights that have been exercised by people for almost half a century. The Court's trajectory has been, generally speaking, to expand and enhance the rights of the people. While those rights can be subject to restriction, even restrictions that have increased over time (the line of cases after Roe demonstrate that, though none have undone the beating heart of privacy of Roe), the wholesale stripping of rights previously established is rare. One could point to, perhaps, the 18th Amendment, the Dred Scott case, or even the Civil War era Amendments, though it is important to note that of those three, only the Civil War era Amendments still stand. (I will leave you to draw your own conclusions as to why.)
Here I will interject my own opinion, which I have not yet so far. Clearing a path to a "nationwide ban" (whatever that means) would not come by one case alone -- it would take a number of cases, and it would take decades to fully eradicate Roe. Even then, there is a very strong argument to be made that a nationwide ban is impossible, because of state constitutional protections on the right to privacy. While the states cannot curtail rights given by the Constitution to the people, they can expand rights (with a bunch of caveats that aren't particularly germane here). There's nothing stopping Connecticut or California or Oregon from keeping abortion legal within their boundaries, because their constitutions can provide for the right.
Incorrect; please read up on the Hyde Amendment.
Incorrect; the legal definition of "human being" does not encompass a fetus. Cf. 1 U.S. Code § 8.
Again, personal opinion, but I believe there has been considerable pushback on the morality and legality of abortion in this country, including, but not limited to, murder of health providers that work with women seeking terminations.
I do appreciate my Constitutional right to privacy! It is one of the reasons why I no longer live in the UK.
Peace out from maven, y'all, and Happy Thanksgiving. 🦃