You have articulated my understanding quite well, as I just don't like to called Sunday the Sabbath Day, prefer the Lord's Day...So let's sum up some basics (for my own benefit):
-pattern of work 6, rest 1 established at creation by God (Gen. 2)
-this pattern was reinforced in the giving of the moral law (Ex. 20)
-God expected the Israelites to observe the Sabbath prior to the giving of the moral law; this, along with the pattern of Gen. 2 leads us to believe that it is an eternal, unchanging principle for mankind
-Leviticus 23:3 teaches that the Sabbath was to be a day of rest and a holy convocation for the people of God
-Jesus said that not one jot or tittle will pass away from the law until the end of the world
-Jesus calls himself the "Lord of the Sabbath" - and we are to conclude that he is still the Lord of the Sabbath
-God's people post-resurrection are clearly shown to be regularly assembling on the 1st day of the week. (for example: Acts 20). This leads us to believe that the day of convocation has switched from the last day of the week to the first day of the week.
Is this accurate?