An extraordinarily long greeting

Following accepted practices, Paul began his epistles with a greeting. However, the greeting in the Epistle to the Romans is extraordinarily long. For the sake of comparison, here is a collection of Paul's greetings in epistles to different churches.

"Paul, and Silvanus, and Timotheus, unto the church of the Thessalonians which is in God the Father and in the Lord Jesus Christ: Grace be unto you, and peace, from God our Father, and the Lord Jesus Christ." (1 Thessalonians 1:1) @51 A.D.
"Paul, and Silvanus, and Timotheus, unto the church of the Thessalonians in God our Father and the Lord Jesus Christ:
Grace unto you, and peace, from God our Father and the Lord Jesus Christ." (2 Thessalonians 1:1-2) @52 A.D.
"Paul, called to be an apostle of Jesus Christ through the will of God, and Sosthenes our brother,
Unto the church of God which is at Corinth, to them that are sanctified in Christ Jesus, called to be saints, with all that in every place call upon the name of Jesus Christ our Lord, both theirs and ours:
Grace be unto you, and peace, from God our Father, and from the Lord Jesus Christ." (1 Corinthians 1:1-3) @56 A.D.
"Paul, an apostle of Jesus Christ by the will of God, and Timothy our brother, unto the church of God which is at Corinth, with all the saints which are in all Achaia:
Grace be to you and peace from God our Father, and from the Lord Jesus Christ." (2 Corinthians 1:1-2) @57 A.D.
"Paul, an apostle, (not of men, neither by man, but by Jesus Christ, and God the Father, who raised him from the dead;)
And all the brethren which are with me, unto the churches of Galatia:
Grace be to you and peace from God the Father, and from our Lord Jesus Christ," (Galatians 1:1-3) @57 A.D.

"Paul, a servant of Jesus Christ, called to be an apostle, separated unto the gospel of God,
(Which he had promised afore by his prophets in the holy scriptures,)
Concerning his Son Jesus Christ our Lord, which was made of the seed of David according to the flesh;
And declared to be the Son of God with power, according to the spirit of holiness, by the resurrection from the dead:
By whom we have received grace and apostleship, for obedience to the faith among all nations, for his name:
Among whom are ye also the called of Jesus Christ:
To all that be in Rome, beloved of God, called to be saints: Grace to you and peace from God our Father, and the Lord Jesus Christ." (Romans 1:1-7) @58 A.D.

"Paul, an apostle of Jesus Christ by the will of God, to the saints which are at Ephesus, and to the faithful in Christ Jesus:
Grace be to you, and peace, from God our Father, and from the Lord Jesus Christ." (Ephesians 1:1-2) @63 A.D.
"Paul and Timotheus, the servants of Jesus Christ, to all the saints in Christ Jesus which are at Philippi, with the bishops and deacons:
Grace be unto you, and peace, from God our Father, and from the Lord Jesus Christ." (Philippians 1:1-2) @63 A.D.
"Paul, an apostle of Jesus Christ by the will of God, and Timotheus our brother,
To the saints and faithful brethren in Christ which are at Colosse: Grace be unto you, and peace, from God our Father and the Lord Jesus Christ." (Colossians 1:1-2) @63 A.D.

Here, we can make some sketchy observations.

1. Without exception, Paul wishes the recipients grace and peace bestowed from God the Father and the Lord Jesus Christ. 
2. To the church in Thessalonia, Paul did not mention any office title. To the church that gave him the most pleasure, he called himself servant (Philippi). To the rest (Corinth, Galatia, Rome, Ephesus and Colossia), he called himself (even insisted that he was) apostle.
3. To only two churches did Paul write in sole authority (Rome and Ephesus). To the rest, Paul included his coworkers (Silas, Timothy and Sosthenes).
4. The epistle to the Romans is a turning point in the sense that Paul wrote to the churches before this epistle. Beginning with the Romans, Paul addresses to the saints in that particular location. Perhaps it was a Pauline theological insight that the Church is community made up of believers who are called to sainthood. It is more than an organization.
5. The church in Philippi was more highly developed than the other churches because bishops and deacons are included in the greeting.
6. Lastly, Paul was an itinerary apostle. He seldom stayed in the same place for a long time except for Ephesus. He set up a church, elected some elders to oversee it and left for other places. Later, Paul would write to the churches he himself had set up with the exception of Rome. Paul wrote to the Romans even though he had never been to Rome.

Let us return to the Romans.
Removing the first and last verses in the greeting, we see his Christological position (Romans 1:2-6). Why did Paul insert such a creed in the greeting to an audience which he had never met before? Perhaps it was an issue the Romans had to handle and Paul would deal with it later in the epistle. Or perhaps it was a kind of identity statement, ensuring the Romans that the gospel he preached would not be too different from what the Romans believed ... or some other reasonable guesses.
I think I have tarried for too long in the greeting of the Romans. I had better proceed ahead.

Dear Lord, bear me on Your wings and help me see farther ahead. Amen.