Your questions deal with a sensitive and much-debated issue in American society today; thank you for writing in with such timely concerns.
First, it should be noted that the Presbyterian Church in America has not yet officially and explicitly adopted a position paper on these topics; but our denomination operates strictly within traditional biblical, Protestant orthodoxy, thus the following comments (hopefully!) reflect our evangelical, Reformed beliefs as derived from the plain teaching of Scripture.
Marriage, as God instituted it in His Holy Word, clearly is between one man and one woman only; this bond is intended for life. Any other "arrangement" (such as so-called "homosexual marriage," bestiality, etc.) is sinful and in blatant violation of Scripture. We therefore do not countenance "homosexual marriage" -- such does not legitimately even exist.
To answer your next question -- what is the PCA's opinion on the ordination of celibate homosexual ministers? -- we really must cut to the heart of the issue. In both testaments the Scriptures condemn sexual desire and activity between members of the same sex as a perversion of God's good creation and intention for humans. This prohibition is not merely an aspect of Levitical law, since fulfilled with the work of Christ; it reaches to the very creation itself and transcends cultures and eras. When Jesus, often marshaled as a supposed sympathizer with the proponents of "same-sex marriage," chose to speak about marriage, he spoke *solely* of marriage between a man and a woman (St. Matthew 19:5). And of course, Moses and St. Paul -- separated by centuries, but both under the inspiration of the same Holy Spirit -- agreed in declaring the sinfulness of any same-sex longings or sexual activities (Leviticus 18:22; Romans 1:26-32).
Those who are ordained to the ministry must be sterling witnesses of the Christian life, especially in matters of sexual purity (I Timothy 3). If single, he must be pure and chaste; if married, faithful to his wife and pure in his thoughts. This means a heterosexual man who in his mature Christian life engages in fornication (if he is single) or in adultery (if married) is not fit for ordination. This means a homosexual man who actively pursues such behavior is not fit for ordination. Now, if he -- heterosexual or homosexual -- confesses his sinful inclinations, repents and desires to lead a holy life both in thought and in deed, he is a fine candidate for ordination *on this count*. A born-again man's personal struggles with any deviant form of sexuality, be it homosexual leanings or heterosexual lust, are a part of his sanctifying walk with Christ, and he is to wage war against such indwelling sin. If a man with homosexual desires confessed the sinfulness of such desires and sought God's grace and help in Christ, he would be every bit as fit a candidate as a heterosexual man struggling with his own lusts, which are no less sinful in the sight of God! The error would arise in endorsing any form of deviant sexuality, be it hetero- or homosexual (or another form).
Your third question dealt with outreach programs targeted at homosexual persons; our outreach programs broadly target sinners! We all are sinners, none worse than the next, all deserving the wrath of a holy God (Romans 3:23). One person's battle with homosexual lust and tendencies is another person's battle with heterosexual lust is another person's battle with outright pride is another person's battle with greed and envy. While we unabashedly call "sin" any form of sexual desire or activity apart from that between a husband and his wife, we do not "pick on" homosexuals as being any worse sinners than heterosexuals. The Scriptures call on them to see their desires and actions as what they truly are -- a violation of God's law revealed in Scripture, as all men are to do in their own hearts and lives.
Our desire is to confront all people with their sinfulness from the Word of God that they might obey the truth (Galatians 5:7), repent, believe on Christ and have eternal life in him. Whether a person struggles with homosexual sin or with selfishness or with any form of evil, our earnest prayer is that he will see his sinful nature (the cause of homosexual sin and, indeed, every type of sin) in God's light (Psalm 36:9), turn from that evil and look to Jesus for life (I Timothy 1:15).