Do you believe in Limbo, or do you think that even infants suffer in the fires of hell, or do you believe that people who die in original sin alone somehow go to heaven (which is what I think the Novus Ordo believes)?

Yup.

Infants do not suffer from the Fires of Hell. They cannot be punished as somebody who has rejected God and has died in mortal sin. Their punishment is the loss of the Beatific vision in Limbo as they have Adam’s sin.

Novus Ordo proposes a new "hypothesis". They say: We do not deny the dogma!, we agree everybody who dies with original sin is deprived of Beatific vision but as the Mercy of God is Infinite, if an infant dies without being baptized, God can “baptize” him/her giving the graces of Baptism moments before the child dies (maybe before the soul is completely separated from the body or something similar)

St. Thomas said "Children while in the mother's womb have not yet come forth into the world to live among other men. Consequently they cannot be subject to the action of man, so as to receive the sacrament, at the hands of man, unto salvation. They can, however, be subject to the action of God, in Whose sight they live, so as, by a kind of privilege, to receive the grace of sanctification; as was the case with those who were sanctified in the womb."

"Souls who depart this life in the state of original sin are excluded from the Beatific Vision of God" is a Dogma of Faith.

If the Church taught that babies unbaptized go to heaven, can you IMAGINE how many people would use abortion as an excuse to "mercy kill" their children?! Think of the implications, and then remember what the Church has definitively taught about entrance into heaven.

You must be baptized, you must be a Catholic, and you must be free from actual sin to be saved. That's it!

Yes, Limbo is a place of natural happiness, but without the beatific vision.  It is for those who were born but died without baptism and who were incapable of actual sin.  Limbo is occupied by babies, young children, and those of infantile mental capability.  For example, the 12 year old son of a Jєωιѕн couple died of pneumonia.  Nathan was born missing most of his brain.  His behaviour was that of a newborn infant.  Perhaps less.  He never focused his eyes, showed recognition of others, was fed by a tube as he could not suck or swallow.  Being Jєωιѕн, he wasn't baptised.  When he died, he was the size of a 2 1/2 year old despite being 12.  He was incapable of committing personal sin.  I could be wrong, but I do not believe God is punishing him with fire.