So, today--in what's probably the last entry in this series (maybe I'll do Catholic 202 someday!)--I'm answering some questions that I've been asked!

(And also: Advent has started!!!!)

What are relics?

This is a good question. They are something that perplex non-Catholics, probably. :)

Relics have to do with saints. Essentially, relics are the bones, ashes, and/or clothing of a saint.

A sign directing you to St. Therese's reliquary, St. Therese retreat house, Columbus, OH. — A sign directing you to St. Therese's reliquary, St. Therese retreat house, Columbus, OH.

A statue of St. Therese. The three items in the foreground are relics from St. Therese.

The relics are divided into classes: first, second, and third. Here's wikipedia:

First-Class Relics: items directly associated with the events of Christ's life (manger, cross, etc.) or the physical remains of a saint (a bone, a hair, skull, a limb, etc.). Traditionally, a martyr's relics are often more prized than the relics of other saints. Parts of the saint that were significant to that saint's life are more prized relics. For instance, King St. Stephen of Hungary's right forearm is especially important because of his status as a ruler. A famous theologian's head may be his most important relic. (The head of St. Thomas Aquinas was removed by the monks at the Cistercian abbey at Fossanova where he died.) If a saint did a lot of traveling, then the bones of his feet may be prized. Catholic teaching prohibits relics to be divided up into small, unrecognizable parts if they are to be used in liturgy (i.e., as in an altar; see the rubrics listed in Rite of Dedication of a Church and an Altar).
Second-Class Relics: items that the saint owned or frequently used, for example, a crucifix, rosary, book, etc. Again, an item more important in the saint's life is thus a more important relic. Sometimes a second-class relic is a part of an item that the saint wore (a shirt, a glove, etc.) and is known as ex indumentis("from the clothing").
Third-Class Relics: any object that is touched to a first- or second-class relic.[38] Most third-class relics are small pieces of cloth, though in the first millennium oil was popular; the Monza ampullae contained oil collected from lamps burning before the major sites of Christ's life, and some reliquaries had holes for oil to be poured in and out again. Many people call the cloth touched to the bones of saints "ex brandea". But ex brandea strictly refers to pieces of clothing that were touched to the body or tombs of the apostles. It is a term that is used only for such; it is not a synonym for a third-class relic.

So basically, relics are either from Jesus or the saints. There are relics of the True Cross, found by St. Helena. Nowadays you'll normally find documentation attached to relics. At the reliquary I visited (above), there were proofs of authenticity framed on the wall next to the relics.

Basically, relics help put us in touch with the divine. Miracles have been attributed to them. But we don't worship them, just like we don't worship saints. But they are holy objects and thus are to be treated with respect.

Does a child have to be baptized before she receives First Communion?

Yes. Baptism is the "entry" sacrament, the sacrament that makes someone a member of the Christian family. All the sacraments build on that one.
A child can go through a child's version of RCIA (Rite of Christian Initiation for Adults--the conversion process for people who either are Christian, but not Catholic, or not Christian at all), or a child can be baptized the way babies are, with additional instruction, since the child is older.

Does the Catholic Church ever allow abortion?

No. That's the short answer.
The long answer, from the Catechism, is here--and I'm posting the whole thing. It's sort of long.

2270 Human life must be respected and protected absolutely from the moment of conception. From the first moment of his existence, a human being must be recognized as having the rights of a person - among which is the inviolable right of every innocent being to life.72
"Before I formed you in the womb I knew you, and before you were born I consecrated you."73
"My frame was not hidden from you, when I was being made in secret, intricately wrought in the depths of the earth."74
2271 Since the first century the Church has affirmed the moral evil of every procured abortion. This teaching has not changed and remains unchangeable. Direct abortion, that is to say, abortion willed either as an end or a means, is gravely contrary to the moral law:
You shall not kill the embryo by abortion and shall not cause the newborn to perish.75
God, the Lord of life, has entrusted to men the noble mission of safeguarding life, and men must carry it out in a manner worthy of themselves. Life must be protected with the utmost care from the moment of conception: abortion and infanticide are abominable crimes.76
2272 Formal cooperation in an abortion constitutes a grave offense. The Church attaches the canonical penalty of excommunication to this crime against human life. "A person who procures a completed abortion incurs excommunication latae sententiae,"77 "by the very commission of the offense,"78 and subject to the conditions provided by Canon Law.79 The Church does not thereby intend to restrict the scope of mercy. Rather, she makes clear the gravity of the crime committed, the irreparable harm done to the innocent who is put to death, as well as to the parents and the whole of society.
2273 The inalienable right to life of every innocent human individual is a constitutive element of a civil society and its legislation:
"The inalienable rights of the person must be recognized and respected by civil society and the political authority. These human rights depend neither on single individuals nor on parents; nor do they represent a concession made by society and the state; they belong to human nature and are inherent in the person by virtue of the creative act from which the person took his origin. Among such fundamental rights one should mention in this regard every human being's right to life and physical integrity from the moment of conception until death."80
"The moment a positive law deprives a category of human beings of the protection which civil legislation ought to accord them, the state is denying the equality of all before the law. When the state does not place its power at the service of the rights of each citizen, and in particular of the more vulnerable, the very foundations of a state based on law are undermined. . . . As a consequence of the respect and protection which must be ensured for the unborn child from the moment of conception, the law must provide appropriate penal sanctions for every deliberate violation of the child's rights."81
2274 Since it must be treated from conception as a person, the embryo must be defended in its integrity, cared for, and healed, as far as possible, like any other human being.
Prenatal diagnosis is morally licit, "if it respects the life and integrity of the embryo and the human fetus and is directed toward its safe guarding or healing as an individual. . . . It is gravely opposed to the moral law when this is done with the thought of possibly inducing an abortion, depending upon the results: a diagnosis must not be the equivalent of a death sentence."82
2275 "One must hold as licit procedures carried out on the human embryo which respect the life and integrity of the embryo and do not involve disproportionate risks for it, but are directed toward its healing the improvement of its condition of health, or its individual survival."83
"It is immoral to produce human embryos intended for exploitation as disposable biological material."84
"Certain attempts to influence chromosomic or genetic inheritance are not therapeutic but are aimed at producing human beings selected according to sex or other predetermined qualities. Such manipulations are contrary to the personal dignity of the human being and his integrity and identity"85 which are unique and unrepeatable.