“Where does the Church teach that God would NOT take a person’s life before baptism while they are being catechized?”

Providence & Baptism

To your first question, the Church teaches that everyone in Heaven from the New Testament period receives baptism (Pope Benedict XII, Benedictus Deus) and that no one can be saved without water baptism (Trent, Sess. 5, Original Sin, etc.). Further, Pope St. Leo the Great and Pope St. Siricius both teach that for unbaptized catechumens in any situation (including accidents, persecutions, etc.), the only way for them to be saved is to actually receive water baptism. They taught that in two of the most important papal decretals in the early Church:

https://vaticancatholic.com/pope-st-leo-the-great-contradicts-baptism-of-blood-desire/

https://vaticancatholic.com/latin-text-oldest-surviving-papal-decree-rejects-baptism-desire/

Ergo, God in His providence will keep all of His elect alive so that they can receive the Sacrament. St. Augustine expressed it well in his final work Against Julian.

St. Augustine, Against Julian, Book 5, Chap. 4: “Of the number of the elect and predestined, even those who have led the very worst kind of life are led to repentance through the goodness of God… Not one of them perishes, regardless of his age at death; never be it said that a man predestined to life would be permitted to end his life without the sacrament of the Mediator [Baptism]. Because of these men, our Lord says: ‘This is the will of him who sent me, the Father, that I should lose nothing of what he has given me.’”

We also see examples of this in the case of missionaries such as St. Isaac Jogues. Here are just two quotes from his life:

The Life of St. Isaac Jogues, p. 92: “Then, most of all [the heathens concluded], the Blackrobes caused people to die by pouring water on their heads; practically everyone they baptized died soon after.”

The Life of St. Isaac Jogues, p. 225: “Two of the Hurons, Jogues learned, were to be burned to death that night at Tionontoguen. He stayed with them on the platform and concentrated his appeals on them. Finally they consented. About that moment, the Mohawks threw the prisoners some raw corn that had been freshly plucked. The sheaths [of the corn] were wet from the recent rains. Father Jogues carefully gathered the precious drops of water on a leaf and poured them over the heads of the two neophytes [new converts], baptizing them in the name of the Father and of the Son and of the Holy Spirit. The Mohawks understood that his [Jogues’] act meant to bring happiness to these hated victims. They raged at his audacity and beat him down, threatening to slaughter him with the Hurons… That night the two Hurons [whom he had baptized] were burned over the fire.”

Other examples can be found in these files:

https://vaticancatholic.com/st-isaac-jogues-st-francis-xavier-vs-invincible-ignorance/

https://vaticancatholic.com/miraculous-baptisms/