I have heard some serious attempts to make the distinctions that I have asked about here. For the most part, however, they mostly are neither Biblical, nor rigorous enough to make clear the distinction in every case. (Which is why I included the specific examples in the OP)
One approach is to say that the Torah specifically declares certain actions as "wicked" or "abominable" and others as merely "unclean" or bans them without editorializing at all. This approach says that the "wicked" and "abominable" actions are moral (and still forbidden) and the others are ceremonial (and not forbidden). But based on that criterion, the actions that are still forbidden include:
* Sharing a meal with Israelites is abominable to Egyptians (Gen 42:32)
* Daily association with foreign shepherds is abominable to the Egyptians (Gen 46:34)
* Hebrew sacrificial practices are abominable to the Egyptians (Exo 8:26)
* Lying with men (Lev 18:22 and 20:13)
* Foreign idols and the gold and silver that adorn them (Deut 7:25-26, 27:15)
* Child sacrifice and/or sacrifice to foreign gods (Deut 12:31, 13:12-17)
* The eating of unclean animals (Deut 14:3)
* Sacrificing diseased animals to the LORD (Deut 17:1)
* Certain (religious) practices of the Canaanites (Deut 18:9-12, 20:18, 32:16)
* Cross-dressing (Deut 22:5)
* Tithing with money earned in the (sexual) worship of foreign gods (Deut 23:18)
* Re-marrying a woman whom you divorced for sexual indecency (adultery?) and who was later married to someone else (and is now divorced again, or widowed) (Deut 24:1-4)
* Having sex with two women who are closely related (Lev 18:17, 20:14)
* Pimping your daughter, or otherwise forcing her to become a harlot (Lev 19:29)
and things that are merely "unclean" include
* Eating unclean animals (Lev 11, passim)
* Allowing abominable idols in the house (Deut 7:26)
* Objects that were offered in sacrifice to foreign idols (Deut 29:17, See also Acts 15:29)
Two problems surface immediately: 1) eating non-kosher is "unclean" but it is also abominable, and 2) some of the things specifically allowed in the letters of Paul are on the "forbidden" list. (Specifically sharing a meal with Gentiles)
The second approach is to proclaim that laws that carried the death penalty are moral (forbidden) and the rest are ceremonial (allowed). That runs into the same problems that the first approach did. Failure to keep the Sabbath was a capital offense, and yet Paul used exactly that as one of his examples of laws we are no longer bound by.
All of the approaches I have come across have similar flaws. There is only one I've heard that is both self-consistant and consistant with Scripture. And it is not a Christian approach, but a Jewish one. It is rooted in the idea of the Righteous Gentile and the distinction between the Law of Moses and the Law of Noah.
If a Gentile wished to honor the God of Abraham, Isaac, and Jacob, it was not necessary for him to convert to Judaism. To do so might even place him in unnecessary danger. Plus, it would subject him to the entire Law of Moses, parts of which might not be possible in a totally Gentile setting. Naaman was even told by the prophet Elisha that he could still bow down in the temple of Rimmon(2 Kings 5).
A righteous Gentile was not subject to the Law of Moses, but he (and all Gentiles) was subject to the Law of Noah. As developed by the Talmdic scholars, the law of Noah consisted of seven commandments:
- Prohibition of Idolatry: You shall not have any idols before God.
- Prohibition of Murder: You shall not murder. (Genesis 9:6)
- Prohibition of Theft: You shall not steal.
- Prohibition of Sexual Promiscuity: You shall not commit adultery.
- Prohibition of Blasphemy: You shall not blaspheme God's name.
- Prohibition of Cruelty to Animals: Do not eat flesh taken from an animal while it is still alive. (Genesis 9:4)
- Requirement to have just Laws: You shall set up an effective judiciary to fairly judge observance of the preceding six laws.
Since all cultures agree (in principle, if not always in practice) with Laws 2, 3, and 7 (and to varying degrees, 4), And a righteous Gentile would accept Laws 1 and 5, they would only have to be specifically taught number 6 and a stricter version of 4. That is, to avoid the meat from non-kosher butchers and to refrain from sexual immorality -- exactly the two restrictions mentioned in Acts 15.
The problem is that, taken literally, the seven Laws are either too specific (Don't eat meat that was butchered before the animal was dead) or too vague and general (don't be cruel to animals). It is necessary to interpret how to apply them in any given situation.
In terms of the examples in the OP:
- Eating unclean meat (Paul tells us that most forms of Uncleanness are OK, but what about actual cruelty duirng preparation and butchery [for example veal or pate de foie gras]?)
- Cross-dressing (Is this a sexual immorality command or a non-mixing command?)
- Working on Sunday (Is this placing a creature [your boss] over God?)
- Having sex with a woman in her niddah (Purity command or sexual immorality command?)
- Sharing a meal with non-believers (Paul's rebuke of Peter was for not eating with Gentile Christians, not random Gentiles. But does this foster non-belief?)
Simply listing the seven laws does not solve the problem of whether certain actions are forbidden or allowed.
In the end, there is nothing to guide us but our individual consciences, and the traditions of the Church.