This is trying to put the need for lots and lots of bible study into a few simple questions, just won't work. All this idea of that Paul was teaching against Torah that is translated as law is for the birds. He wasn't. He was preaching against the Jews saying that things were the same as before Christ was crucified, and that gentiles had to all the Jew things to be accepted.
In order to understand "Sabbath" it would take every scripture about it and put it all together, starting in the second chapter of Genesis. People that use the word rest to say it explains Sabbath are just not using good thought.
The feasts also need to be studied, and they have a very different function than physical circumcision, and if you decide what God meant by them and how they are to be used, it would take study of the feasts. By 300 years after Christ, it is pretty well decided to use the tradition of Christmas and Easter to replace them, so those replacements would also need to be studied.
To top all this study and thought about scripture, it also requires a need to find out about what this "disobeying" has to do with our Christian walk in God's eyes.
Many read scripture from the idea of "down with anything of the Jews" thought. Many read it thinking Judaism is all just terrible. That preconceived thought isn't going to result in any sort of truth. If you once found any copies of the writing of Constantine who gathered these ideas to use to help his power, for anyone who feels they were created in love by a heavenly Father, they could understand the down with the Jews thought that influences understanding of the truth of what Paul was against.