If one does not assume every word of a Pauline letter to have universal meaning, how does that help the reader?
Assuming not every word of a Pauline letter to have universal meaning would help the reader understand Paul's own perspective on his letters. From his perspective, his letters were not equivalent to the utterances of prophets of old, as he says from time to time that he thinks he speaks the mind of God whereas prophets declared they spoke the mind of God. Also from his perspective, he does not think that his letters comprise an addition to Scripture since he admonishes readers to search Scripture for guidance and answers. As a Jewish person, Paul would never entertain the thought that his letters of admonition were an addition to the Torah. The reader may further be helped by having a better definition and delimitation of Scripture and what constitutes a valid addition to the authority of Scripture, which, again, is the Torah.
Yes, we need to remember above all that to Christians, the Bible is not like the Quran, for example, where every word is believed to be set in stone. By contrast, the Bible is recognised to consist of a series of different types of literature, written during different periods of history in different contexts and to different audiences. In particular, the Pauline Epistles are recognised as often being occasional letters, in that they were written in response to different issues or struggles that specific churches in specific geographical locations were facing. Thus it is ridiculous to assume that we can take every word in the Bible and apply it to our lives today. What we need to do is look to the general principals that such specific guidance as women must cover their hair points towards.
It helps incredibly. The Bible is like all literature in that context is everything. Paul was not writing a "new Torah" for the Christian Church, he was writing letters to real people experiencing real contemporary problems. The early church fathers canonized his letters because they believed his writing was inspired by God, but these writings were much different from God directly handing down the 10 Commandments to the Israelites. Paul's letters reveal his efforts to guide (as he allowed the Holy Sprit to guide him) early churches as they tried to sort out the meaning of life and mission after the world changing events of Jesus' life, death, and resurrection. Because the early Christians of Paul's day embraced the belief that God's kingdom had come and consequently followers of Jesus had been given new life, they believed they had also been given a new context to which to live. But that is easier said than done, especially when it came to issues like Jewish practices and incorporating Gentiles into the family of God. Paul's letters address how individuals and the church body should live and act in this new context, as they dealt with issues such as should they eat meat sacrificed to idols, should they require Gentiles to be circumcised, how should they choose leaders in the church, and many more.
Much of Paul's writing is certainly universal, but he dealt quite a bit with many cultural issues specific to the time and place of the original recipients. Examples of universal commands by Paul would most certainly include, but not be limited to, his request that Christians walk in the Spirit, be in Christ, forgive each other, and die with Christ and be raised with Christ. However, other commands would best be understood as relating to specific cultural issues such as his instructions on women being silent in the church and not teaching a man.
I wouldn't classify those verses as universal for all churches and all times because the context of his letters reveal that he was not forbidding all women to never say or teach anything in the church because in I Corinthians 11:5 he says, "every woman who prays or prophesies with her head uncovered dishonors her head." Even though he later says in I Cor. 14:33-34 that women should remain silent in the churches, this can't be taken as a universal command for all women to never speak a word in church because he has already established proper ways for women to speak in church when prophesying.
Another example could be in I Timothy 2:9 when Paul says that women should not have braided hair or gold or pearls. Most Christians would say that this command was due to cultural taboos and therefore not necessarily relevant in modern circumstances, but the main point Paul makes about women dressing modestly is understood as universal.
Obviously interpreting the Bible is always debatable and controversial, not least of which the passages I brought up, but a proper understanding of Paul's letters should not be about following all his commands literally as if they were like the Torah to the Israelites, but rather taking into account his original audience and wrestling with the entire story and context of the Bible.