|The parable of the Prodigal Son (Luke 15:11-32) is an interesting and sometimes difficult parable, but to say that the Church will attempt to shut down any questions about it is unfair, and patently false. In fact, the Church has already answered many of the questions in serendipitous13's writeup, through Sacred Scripture and through other documents, and through the teachings of tradition. (If you attack the Catholic Church, please learn her positions first.)
First of all, Jesus in this parable does not say that we should "celebrate apologetic irresponsibiliy and neglect hard work."
Clearly in the parable, the father is happy because his wayward son has returned, and it is the returning that gives him joy, not the sin he has committed. This is analogous to giving a child a reward for improving her grades. Are we rewarding her for having poor grades in the first place? Of course not! Also, this parable was given in the context of many other discourses. The same God in the same Gospels told people not to commit any of the sins the wayward brother committed, to follow the commandments, love God, and be faithful (e.g. Matthew 19,16-21; 23,37-39).
Regarding the question over who will be more celebrated in heaven, the devout follower or the deathbed convert:
First of all, Christ has made it clear that some will be higher in heaven than others, and it has nothing to do with this parable. God is overjoyed when a lost sheep returns, but in terms of place in heaven, after the Father and Christ at his side, the lowest now shall be highest then. The Gospel is clear that what gets you merit in heaven isn't waiting until you are about to die to convert; rather, it is being humble, poor, meek, constant, and ever-forgiving (e.g. Matthew 19,30). The student who improves her grades might get rewards, smiles, handshakes, and congratulations (and rightly so). But her overall GPA will still be lower than the student who worked hard throughout (also rightly so). The Gospel repeately supports this position; taking one parable out of the context of others is misleading.
Regarding the forgiveness of people after they die:
To clear up confusion, The Catholic Church does not hold the perverse view that God will not forgive you just because you are a soul whose body has died. If you are not ready for heaven but have sin, you will be cleansed in purgatory. That is why we pray for the dead. God is not a vampire who only cares for your body; in fact, the Gospel says (paraphrased): do not fear those who can take your life, but fear God, who is in control of your soul. Because God wants to forgive anyone, dead or not, and only sends those to hell who are stained with mortal sin and choose of their own free will to permanently reject him, He is the ultimate forgiver. Such a great forgiver that we who read the parable of the Prodigal Son are sometimes shocked by how generous He would be to the son who returned, when we weaker, unenlightened humans would seek revenge, or hold a grudge, or make him accountable (See the Universal Catechism, paragraphs 1030-2, 1855-8, 1861). Note: the situation is more complicated when the person is question is unbaptized, see my writeup in the node: Limbo.
Finally, regarding waiting until before death to ask forgiveness:
You cannot fool God! God will be overjoyed if you return to him with repentence, but there are two factors that prevent you from getting away with converting to God at the last minute. First of all, you are still responsible for all the sin you have committed. You must confess, if not to a priest than at least personally; you must repent; and you must go through penance, either on Earth or in Purgatory. Secondly, if you purposely wait to ask forgiveness in order to have more fun sinning, that itself is a sin! And you have to honestly repent of it and do the extra penance! (See the Universal Catechism, Part 2, Section 2, Chapter 2, Article 4: Penance and Reconciliation).
To me this parable is the epitome of all other Lucan parables, because it exemplifies the way in which Jesus communicated difficult concepts. If the idea was: do good and you are rewarded, do bad and you are punished, there would be no need for parables. There would be no need for a New Testament and Covenant! All that stuff was covered in the Old Law. Jesus' teachings go against the grain. He ate with sinners and prostitutes, talked with and taught women, praised the compassion of a good Samaritan (a foreigner of a nation hostile to the Jews), taught to forgive and reward people even when it doen't make sense according to human societal values, taught to sacrifice one's self for His cause rather then fight with arms. There is a reason that the "upright," rich, confident, law-abiding people on top wanted to crucify him. Not that we shouldn't be upright and confident also; be wary of trying to oversimplify Christian teaching.
For more on this line of reasoning, see the great node: Beware of finding a Jesus entirely congenial to you.
Tiefling suggested citing the Anglican prayer (from Prayer C, used during Lent in Rite I, according to my research, but I'm not Anglican):
Although we are unworthy, through our manifold sins,
to offer you any sacrifice,
yet we pray that you will accept this
the duty and service that we owe.
Do not weigh our merits, but pardon our offences,
and fill us all who share in this holy communion
with your grace and heavenly blessing;