This is four separate questions:
What are some of the official explanations for why it's OK for Jews not to follow the law today? For example eat bread on passover, or work on Yom Kippur? How are the above verses addressed?
How did Christians officially address these words of Jesus throughout history, when they taught that Jews shouldn't follow some or all of the Law of Moses (for example the ceremonial laws)? What do they think it means to be called least in the kingdom of Heaven?
Jesus told a man how to get eternal life. If Christians do not consider following the commandments essential to salvation, why did Jesus say what he said?
Why would they ask Paul to dispel these rumors and in fact affirm that Paul himself is living in obedience to the law?
I commented, "Definitely split it into four questions, and specify what tradition you want to hear from. Different denominations will answer these questions differently." Then I flagged it as too broad. It's been over a month. (Edit: No it hasn't. I made a mistake looking at my flagging history when I wrote that.) The flag was deemed helpful, but the question remains open.
I actually think questions 2 and 3 could be combined into one question. Question 1 may be a duplicate of To what extent does the Law of Moses still apply? but I'm not sure (I'm looking at the top-voted non-accepted answer, which is a great overview but not very thorough). But I do think each of the three (or four) questions would need to specify a tradition.
As it is, the mega-question, with all three/four questions together, seems way too broad. I would love to provide an answer to each of the questions, but with them combined, it just doesn't seem practical.