a. by Larry Bray: A moral law is one that all men are bound to. Ceremonial laws were done by the priests, not by all men Civil laws were done by the civil magistrate, not buy all men There are also laws of particular equity and general equity. Laws of general equity were binding on all men while laws of particular equity were binding only on the Jews in order to show a difference between them and the Gentiles. Dietary laws were of particular equity Generally speaking all laws are moral but have different spheres in which they are limited to. Strictly speaking moral laws are those commanded to all men
b. by Nick Napier: As there are a couple of men on your post with whom I would disagree---and I do not care to "get into it" with them, I thought I'd try to help you with your questions:
a. A moral law is a law that flows from and is essential to the character of God. Positive law is a law which God ordains for His own purposes---often for testing His people. Ceremonial laws are those specific laws which were given in the Mosaic economy which were to point to Jesus as our only hope and Savior.
So then, the 10 commandments each flow from the character of God---He will not tolerate false worship b/c He is worthy of perfect worship (& on we go down the line---He gives us 1 in 7 as a rest b/c ultimately He is our rest...etc.) Positive law--example, do not wear mixed fabrics or eat shell fish. God gave these to separate His (theocratic Nation of Israel) from the rest of the world--they are not rooted in His character, and so He is free to change them with the administration of the New Covenant in Jesus. (Acts 10). Ceremonial law is that which was designated to point to Jesus and was fulfilled by Him----sacrificing bulls & lambs.
Since the moral law is demonstrable of the character of God, it is irrevocable---the Sabbath is a part of that. Its principle is acknowledged by its change and perpetuity in the NT. (Jonathan Edwards argues the case well, here: http://www.biblebb.com/files/edwards/sabbath.htm)
Some of the reason for such distinctions in laws is that we are no longer the theocratic nation of Israel, but are Israel in its fullness---that is a spiritual kingdom. Chapter 19 of the WCF does a good job of sorting through these things.
Fasting is not a moral law. Marriage is a creation ordinance---but the ordinance is that those who are married are to "be fruitful & multiply"---there are eunuchs for the Kingdom of God (as Jesus and Paul demonstrate; further if it meant that all must be married, then Jesus would have been in sin & we know that's not the case).
As far as work---work is good, God worked, but rested from His labors on the 7th day; so, we rest.
For h. see WCF 19.1----the people before Moses knew the moral law of God---it was inscipturated with Moses. So that it was passed down it was the law written on their hearts, as it were.
c. Most helpful: http://wscal.edu/resource-center/resource/the-law-and-the-sabbath
d. A good resource: http://heidelblog.net/2013/11/resources-on-the-doctrine-of-sanctification-and-the-third-use-of-the-law/
e. another page: http://feedingonchrist.com/the-third-use-of-the-law-and-finished-work-of-christ/