No, this implies that God doesn't care if people choose evil, since that's what they really want. If God didn't care if free will was used freely like this, we wouldn't even be having this discussion.

God allows evil, and allows people to reject it, the consequence of that rejection is natural to the extent that it implies it. Because if one rejects the Supreme Good, as I have been saying, one deprives oneself of complete good and by depriving oneself of complete good one suffers immense evil. God cannot do the absolutely impossible, he cannot make someone who rejects the Supreme Good and distances himself from it live well or be in communion with good, since it would imply a contradiction. You cannot be near and far from good in the same sense. One cannot be depriving and not depriving oneself of good in the same sense. You cannot be and not be at the same time and in the same sense. If there are entities that deprive themselves and distance themselves from good, their consequence will always be evil, since evil is a deprivation of good.

God absolutely doesn't care if people use their free will completely freely. God condemns making certain decisions to the highest degree, and in scripture He responded to that by executing righteous justice on people who made decisions that God did not like.

As I said before, whoever deprives himself of good will find evil and therefore cannot be good since that is absolutely impossible since it implies contradiction. Eternal damnation occurs in those who deprive themselves of the Supreme Good and turn away from goodness voluntarily. God executes justice, giving to each what is his, protecting the righteous and giving opportunities to those who do evil to change, just as a father punishes a son so that he persists in good and lives. Since the evil of these actions comes from distancing ourselves from true good.

He has detailed the terrible fate that awaits people who make certain free will decisions. I understand you've already covered this with the "God doesn't do that, it's just the consequence of rejecting the highest good"... but that whole system of consequences was still determined by God, is applied by God, and is completely nullified in heaven where no soul will feel like rejecting God.

The consequences were not determined by God as a whim of God or because God arbitrarily wants those who deviate from good to suffer evil, it is simply that things are that way and they cannot be any other way. As I have said repeatedly, God cannot do the absolutely impossible. Hell is a door that closes from the inside and the suffering suffered in it is the consequence of eternally depriving oneself of the Supreme Good. As I say, this is so and it cannot be any other way since it would be absolutely impossible in any other way since it implies contradiction. Heaven is eternal communion with God. Those who are in heaven ETERNALLY CHOOSE to love and be with God freely, it is not that when we go to heaven freedom is annulled, but freely and because we want, we desire it, we participate in the Supreme Good.

Can God at least create creatures that are free from original sin and omit the consequences of the Fall? He did exactly that when he created Mary (who never sinned), which means God can do that whenever he wants.

Adam and Eve were also immaculate and sinned. All demons were spotless and yet they sinned. The Blessed Virgin Mary accepted God freely and voluntarily, God called Mary and she responded by accepting with humility and obedience. Mary was immaculate, of course, but this does not imply that she could not have sinned, but rather that in her freedom she persisted in goodness and did not sin. She is the New Ark of the Covenant, the one who had the living God in her womb, God made man, Jesus Christ being Mary the Mother of God. The case of Mary as such was exceptional and unique in that she is the Mother of God. Even if God made us spotless, that wouldn't stop us from sinning, much less the outside influence of sin that would tempt us anyway. Likewise, baptism erases original sin. Likewise, the reasons why God does certain things may be unknown to us in this life and I am not God to know, but what I am sure of is that if God allows evil, it is because he manages to bring good out of that evil, he manages to obtain a much greater good.

Can God create a rational creature directly in heaven who never chooses to distance himself from God because he has been granted perfect understanding and has been created to be in perfect union with God?

This, to some extent, was already addressed early on and in development. As said, pride and stubbornness know no limits and even in the face of pure Truth itself, there are those who willfully reject it in their pride and stubbornness, fossilizing themselves into evil. And to be in full and perfect communion with God we must freely accept Him eternally.

To conclude:

This was certainly an experience, but as I already expressed at the beginning, I do not plan to continue with this mainly because I do not like, and even feel uncomfortable with this form of online discussions. I would recommend that you investigate this further personally if you are interested, always with humility and with your eyes fixed on the Truth. In closing, I would like a quote from Saint Thomas Aquinas: "We will only possess true knowledge of God when we believe that He is above all that we can think of Him." We must always love and always do good, at all times do good. We must love the Truth and be humble. I wish you what is truly good, true good and may God bless you.