While I find your interpretation of these passages on essential need for baptism to be interesting, I don't find them historical. Baptism has always been a requirement in the Church of Christ. We will have to disagree on this matter.
Besides the many biblical references I gave, these references from early Christians on the nessesity of baptism may interest you:
"For, in the name of God, the Father and Lord of the universe, and of our Saviour Jesus Christ, and of the Holy Spirit, they then receive the washing with water. For Christ also said, "Except ye be born again, ye shall not enter into the kingdom of heaven." Justin Martyr, First Apology 61, in ANF 1:183.
"And dipped himself," says [the Scripture], "seven times in Jordan." It was not for nothing that Naaman of old, when suffering from leprosy, was purified upon his being baptized, but [it served] as an indication to us. For as we are lepers in sin, we are made clean, by means of the sacred water and the invocation of the Lord, from our old transgressions; being spiritually regenerated as new-born babes, even as the Lord has declared: "Except a man be born again through water and the Spirit, he shall not enter into the kingdom of heaven." A fragment attributed to Irenaeus, in ANF 1:574, brackets in original.
"And do not think, though you were more pious than all the pious that ever were, but if you be unbaptized, that you shall ever obtain hope. For all the more, on this account, you shall endure the greater punishment, because you have done excellent works not excellently. For well-doing is excellent when it is done as God has commanded. But if you will not be baptized according to His pleasure, you serve your own will and oppose His counsel. But perhaps some one will say, What does it contribute to piety to be baptized with water? In the first place, because you do that which is pleasing to God; and in the second place, being born again to God of water, by reason of fear you change your first generation, which is of lust, and thus you are able to obtain salvation. But otherwise it is impossible. For thus the prophet has sworn to us, saying, "Verily I say to you, Unless ye be regenerated by living water into the name of Father, Son, and Holy Spirit, you shall not enter the kingdom of heaven." Clementine Homilies 11:25-26, in ANF 8:289-290.
Nay, he that, out of contempt, will not be baptized, shall be condemned as an unbeliever, and shall be reproached as ungrateful and foolish. For the Lord says: "Except a man be baptized of water and of the Spirit, he shall by no means enter into the kingdom of heaven." And again: "He that believeth and is baptized shall be saved; but he that believeth not shall be damned." Apostolic Constitutions 6:15, in ANF 7:456-457.
Also, here are some great examples of ancient baptismal fonts. There were permanent fixtures that were part of the communities. I'm also throwing in a interesting photo of a brass Catholic font from the 12th Century that will be sort of recognizable to some familiar with the fonts in LDS temples.
