Donald, your comments are very interesting and well-reasoned, and I agree with a lot of what you said. Let me say this: If Jesus rose from the grave on Saturday rather than Sunday, and if Acts 20:7 and I Cor. 16:2 don't mean that the early church met on Sunday (see Daniel's comments), then the 1st-day sabbath is untenable.
However, I disagree with part of your comments:
I would assert that Col. 2 is similar to Jesus' comments on the commandments of men in Mt. 15:1-20; Mk. 7:1-23; see also Titus 1:14, and that the ordinances we are not to be subject to seem to be listed in the passage (Col. 2:16, 21) and have their root in the Old Testment. The "rudiments of the world" are the Pharisaical observance (combined, as you said, with pagan philosophies such as Gnosticism in the case of this local congregation) of these laws that, though binding in the O.T. (the laws as well as all their spiritual principles, but not the superficial man-made regulations), now merely symbolize Christ (not to say that there are not spritual applications for us today). Rom. 14:5-6 also seems clear that observing particular feast days is optional, not binding.
I mainly agree with your comments on Acts. However, Paul's preaching to unbelievers (whether Jewish or otherwise) cannot be considered to be a church meeting of a group of believers.
You have a very interesting point about when Jesus rose from the grave. I think you're implying that Jesus rose late Saturday afternoon, right? But then why didn't the word get out sooner when it did, considering how shook up the guards were? Furthermore, I think that wouldn't quite fulfill the three days and three nights (Mt. 12:40) -- we need Thursday night (just before sunset like you said), Friday morning, Friday night, Saturday morning, Saturday night, and Sunday morning to make three days and three nights. The traditional timeline of Friday night, Saturday morning, Saturday night, and Sunday morning is also too short to count as three days and three nights imho. We need two full sabbath days (Friday and Saturday) between the day of crucifiction and the day of resurrection.
(I am aware of the debate about the last part of Mark 16, but I tend to think that it was in fact inspired. But that's another lengthy discussion.)
I appreciate your basing everything you've said in the Scriptures. I can see that it's not extremely clear that 1st-day sabbath is the way to go, and I wish things were more clear so we could agree. Whether that problem is due to a change being made by God without much discussion given to it in the Bible, or due to confusion caused by an unscriptural change, I guess that's the question. I would be interested to know the practice of the church between A.D. 70-313. Thanks for your comments.