“Not all can accept this word, but only those to whom it is granted. Some are incapable of marriage because they were born so; some, because they were made so by others; some, because they have renounced marriage for the sake of the kingdom of God. Whoever can accept this ought to accept it.” (Matthew 19:11–12)
“He who marries does well; and he who refrains from marriage will do better.” (1 Corinthians 7:38)
I’m not sure what passages talk about the individual churches being individually governed, but every church has a certain degree of autonomy, and dioceses have fuller autonomy, though they of course have to accept official Church teachings.
“Calling no man father” is arguably not referring to the word itself:
“I do not write these things to make you ashamed, but to admonish you as my beloved children. For though you have countless guides in Christ, you do not have many fathers. For I became your father in Christ Jesus through the gospel. I urge you, then, be imitators of me.” (1 Corinthians 4:14-16)
“And Stephen said: ‘Brothers and fathers, hear me. The God of glory appeared to our father Abraham when he was in Mesopotamia, before he lived in Haran…’” (Acts 7:2)
There are also a few other New Testament passages that refer to Abraham as a spiritual father. So either Christians didn’t take Jesus seriously, or he meant something else: that we need to recognize God as our ultimate father and teacher, and not look up to people who adopt titles for themselves without putting into practice what they teach, or do not provide valuable guidance (Jesus also said to call no man rabbi/teacher earlier in the passage). Keep in mind that Jesus was a known user of hyperbole.
Baptism can be understood as superceding circumcision, which was performed when a baby was eight days old. It makes sense, therefore, to stick with that age. Additionally, a few passages make reference to people being baptized along with their “entire household.” Presumably, this would include children. After looking for them, I cannot find any Biblical passages that state that one must receive instruction of the gospel before baptism. (The Church does, however, require adults to go through the RCIA (Rite of Christian Initiation), which includes instruction on the gospel and Church teachings, before being baptised). I have not come across a passage that states that one must fully understand the gospel in order to be baptised, only that this is necessary in order to be saved, which is not the same thing according to Catholic teaching (and the Bible).
When you say that the original manuscripts called for full immersion, I assume you are referring to the fact that that is implicit in the Greek word for baptism. I fail to see that as being sufficient reason to require full immersion, as it is the spiritual aspect of baptism that is most important, with the physical symbolism being secondary.
A place for everything, and everything in it's place, but I'll respond to this list here.
Paul was a missionary who's primary concern was spreading the Gospel far and wide. This work is very difficult for those with wives and children. It was not so difficult in the established local congregations. Paul recognized that in the polities of the empire, the city states and small provinces, it was important to have well grounded, sober, decent men with an understanding of how normal healthy human communities should function. For this you need good husbands to one wife, where at all possible.
The early Church, before Constantine and his Luciferian, Mithratic, Mystery Babylonian priests got into the act, was a peculiar nation organized as a sort of confederation of local congregations giving respect and accepting guidance from a great council or Sanhedrin located in Jerusalem and headed by James, son of Mary, brother of Jesus. The RCC functions as a completely centralized absolute tyranny.
Jesus specifically commanded against the use of the title or style 'Father' as an HONORIFIC. Of course you could address your biological father as such, as well as your biological forebears, as with Stephen and Abraham. Abraham is also LIKENED to a father in the spiritual sense, but that isn't about elevating some mere mortals you meet in everyday life. In the Epistles, Paul sometimes LIKENS himself to a father in his function of raising the congregations, he wasn't demanding or suggesting that he be formily addressed so as a form of exaltation. In these ancient societies, the Pater Familias held tremendous power and commanded great respect over the households. Petty tyrants in politics and the mystery cults would also insist upon this title as a way of glorifying themselves and confusing their subjects into believing that their corruptions and usurpations should be regarded as a proper love of father for children.
As for Baptism, I confess it's unclear to me. I'm a 'Form follows function' type of guy. I prefer to look at purpose, function, objective first, and regard particular ritualistic forms as secondary. The objective is to save the baptized through Christ. If infant Baptism assists to that end, well enough. If it leads to forgetting or a false sense security, maybe the infant baptized should have their baptisms renewed.