1 Corinthians 10:2

And were all baptized unto Moses in the cloud and in the sea (KJV)

Then: Jewish believers in Christ knew intuitively that they were a continuous part of God's plan and now were personally and fully blessed by the Lord's spirit through baptism (immersion). The Gentile Corinthians didn't have that connection. Paul had to make one and he does. It's a quid pro quo action. The Corinthians gave God their belief in him and his son. God gave them his promised inheritance, salvation through Christ. Being baptized is the connection. Like the Israelites following Moses, both Jews and Gentiles following Christ moved into a new promised land, a place in the Lord's kingdom (Baker, p. 142). Claimed and loved by the jealous God of Israel, the Corinthians need to ensure that all their actions keep them within the laws of Christ (Dunn and Rogerson, p.1331).

Now: Paul's idea is not seen as being new or different. Believers accept it as a fact, a solid comparison or analogy heard so many times that few take time to think about it.

Extra source: Cornerstone Biblical Commentary 1 Corinthians (William Baker), 2 Corinthians (Ralph Martin & Carl Toney), ed. by Philip Comfort. Carol Stream: Tyndale House Publishers, c2006.
Eerdmans commentary on the Bible by James D. G. Dunn, John William Rogerson on line at http://books.google.com/books?id=2Vo-11umIZQC&pg=PA1353&lpg=PA1353&dq=1+Corinthians+9+commentary&source=bl&ots=5QeQaYWrMS&sig=S5F3KcA_TvNMyywqRiimySoUYtc&hl=en&ei=QqHPSouICIWj8AaZxqyABA&sa=X&oi=book_result&ct=result&resnum=8&ved=0CBkQ6AEwBzgU#v=onepage&q=1%20Corinthians%209%20commentary&f=false

1 Corinthians 10:1

Moreover, brethren, I would not that ye should be ignorant, how that all our fathers were under the cloud, and all passed through the sea (KJV)

Then: For sure the Jews already knew this story, but they may nave needed to see how it fit with Jesus' teaching. After all, it took Paul several years of study to change from a Jewish mindset to an understanding of where God was headed throughout all those years before Christ. The gentile Corinthians needed to know the same information and may have also been attracted to the "knowledge" aspect. Anything new is good. And besides, who wants to be ignorant? Although Baker (p. 137) thinks they heard it before - when Paul was actually among them. Baker also keys in to the cloud as an often present sign when things spiritual happened - the ascension and the transfiguration, for instance. Dunn and Rogerson (p.1334) explain that previously Paul's argument against eating idol meat was positively oriented and that with this verse he's heading to the negative. So there's "method," just not easy to recognize.

Now: Fairly often people who know the Bible stories lack the ability to recognize their teaching points. It takes someone else to stand back and say, "Hey your problem is exactly the same as 'so and so.' Remember what he/she did?" Believers today need Christian friends and teachers to do for them what Paul does here. They need to listen, not just think that guy is going off on a tangent with unrelated, out-of-the-box stories. We all need "Paul's" in our lives.

Extra source: Cornerstone Biblical Commentary 1 Corinthians (William Baker), 2 Corinthians (Ralph Martin & Carl Toney), ed. by Philip Comfort. Carol Stream: Tyndale House Publishers, c2006.Eerdmans commentary on the Bible By James D. G. Dunn, John William Rogerson on line at http://books.google.com/books?id=2Vo-11umIZQC&pg=PA1353&lpg=PA1353&dq=1+Corinthians+9+commentary&source=bl&ots=5QeQaYWrMS&sig=S5F3KcA_TvNMyywqRiimySoUYtc&hl=en&ei=QqHPSouICIWj8AaZxqyABA&sa=X&oi=book_result&ct=result&resnum=8&ved=0CBkQ6AEwBzgU#v=onepage&q=1%20Corinthians%209%20commentary&f=false
Additional source note: The on-line advertised book First Corinthians: A commentary for today does not say if it covers any information after Chapter 8. The Contents section is abbreviated in the Google Book previews. Book is probably helpful. It does have self-study questions. On-line evaluation here: http://books.google.com/books?id=cKpy9maLuiQC&pg=PA15&lpg=PA15&dq=Corinthians+then+and+now&source=bl&ots=ZdIs9pRvsC&sig=ZMrn7l18_-IoMfNxStR3P0RynXs&hl=en&ei=lG7QSqvcB5PGlAewrNCoCg&sa=X&oi=book_result&ct=result&resnum=6&ved=0CBoQ6AEwBQ#v=onepage&q=Corinthians%20then%20and%20now&f=false

1 Corinthians 9:20

And unto the Jews I became as a Jew, that I might gain the Jews; to them that are under the law, as under the law, that I might gain them that are under the law (KJV)

Then: How could a Roman citizen who looked free, be a slave? The Corinthians needed Paul's explanation. When he worked with the Jews he submitted to all the Jewish laws of the Old Testament. But he did it for a purpose - that of winning them to Christ. This is the first example of ways Paul worked as a slave (Wright, p. 115).

Now: The statement "When in Rome do as the Romans" applies here. Even though secular, it shows the wisdom of getting to know people where they are by showing respect to the salient points of their culture and behaviors.

1 Corinthians 9:7

Who goeth a warfare any time at his own charges? who planteth a vineyard, and eateth not of the fruit thereof? or who feedeth a flock, and eateth not of the milk of the flock? (KJV)

Then: Paul continued explaining that everybody expected and deserved to be paid (receive food and sustenance from) for their work. Robertson and Plummer (under IX, 7) note the soldier worked for pay, the vine planter was a small business owner, and the shepherd worked as a slave. Congregational members at Corinth surely had more prestigious work, but would understand the principle.

Now: Members of church congregations expect and receive pay for their work. The principle is the same for ministers and staff. They deserve payment no matter their occupation.

Extra source: A Critical and Exegetical Commentary on the First Epistle of St. Paul to the Corinthians by Archibald Robertson and Alfred Plummer (Charles Scribner Sons, 1911) online at http://www.archive.org/stream/stpaulcommentary00robeuoft/stpaulcommentary00robeuoft_djvu.txt

Following the Interpolation

I Corinthians 7:2-10

Then: Paul backs off from the severity of his statements (one more reason it is not an interpolation) and slips into discussing the portrait of a successful Christian (Wright, p. 75-79), himself. He works hard, suffers disappointments, worries about the Corinthian church, comforted by God and rejoices in the Corinthians' progress towards salvation.

Now: Usually overlook the difficulties of living a Christian life and only notice the successes and joys. If problems are mentioned or talked about, it's always in the past about those which have been overcome. Sometimes close friends are asked to pray, but usually the problems are private. Paul is open for a purpose. He wants these Corinthians to move towards victory. We don't know how much or how often we should allow others to see our own struggles.

I Corinthians 4:11

Even unto this present hour we both hunger, and thirst, and are naked, and are buffeted, and have no certain dwellingplace (KJV)

Then: Here are five worldly life circumstances of the apostolic leaders. These differ considerably from the members of the church in Corinth. Fee (p. 178) talks about the chiastic order of the list, a literary set-up characterized by saying things forwards and backwards. In several upcoming verses, Paul goes from the end to the beginning of this list in discussing each one. That discussion also includes a sixth problem (menial labor) listed in the beginning of verse twelve.

Now: To concentrate on comparing prosperous Christians with impoverished ones is to go a little off track. Those who work hard and are blessed can do a lot to improve the life circumstances of the less fortunate. The point is not rich versus poor, but the willingness to sacrifice for the kingdom. The issue is better seen as a matter of pride and sense of superiority over other believers.

Extra source: The First Epistle to the Corinthians by Gordon D. Fee (Eerdman's 1987) online at http://books.google.com/books?id=XlBp10nUTXAC&dq=Gordon+Fee+Bible+commentator&printsec=frontcover&source=in&hl=en&ei=SwLNSu3nA4v6Mf2XlDo&sa=X&oi=book_result&ct=result&resnum=12#v=onepage&q=&f=false