Hopefully, someone will correct if I'm wrong, but I believe the superscriptions show up in most original manuscripts. For the most part they are descriptions of the Psalms' liturgical use ('for the End'--i.e., of a service), or a brief commentary on author (psalm of David) or circumstances of authorship. I can't recall ever seeing them used as anything but to contextualize the Psalm in its original (Jewish) usage.
The statement "For the End" makes a lot of sense as far as being used at the end of the service. . .I've read other commentary (can't for the life of me remember where, now. . .but I'll see if I can find it) that it is for the 'end time' meaning the time Christ Jesus actually walked the earth. Ah, the commentary on Psalm 9 vs 1 in the Orthodox Study Bible discusses this.
I know that many of the Psalms are prophetic. . .so I suppose that is what I was wondering about this specific superscript. . . is this a prophetic utterance on behalf of the Theotokos? Or the Church? Is there anything written in the Holy Fathers that makes any statement concerning this? There is not commentary in my bible concerning it.
Fr. Patrick Reardon has written a little article on the subject of the psalm inscriptions. You can read it here:http://www.orthodoxytoday.org/view/reardon-psalm-inscriptions
St. Gregory of Nyssa wrote a commentary, called On the Inscriptions of the Psalms
, which is specifically about these 'header' verses. It is available on Amazon.com and elsewhere, and well worth the price, if you are interested in this subject. Incidentally, while every psalm in the Greek Septuagint has a heading, that was not the case in the original Hebrew, which is why, in Orthodox Psalters, which are based on the Greek text, the header for Psalm I reads, "A Psalm of David. Without superscription in the Hebrew." Interestingly, this difference is taken into account in the verse numbering in most Orthodox Psalters. If the superscription exists in the Hebrew, then that verse is counted as Verse I (Verses 1 and 2, in the case of Psalm 59). Oddly enough, Holy Transfiguration's Psalter According to the Seventy
does not follow the traditional versification of the Greek, Latin and Church Slavonic translations of the Septuagint.
As for your specific questions:
"Unto the end" or "For the end": St. Gregory writes (p. 102), "Therefore, the next psalm [Ps. 4] has the inscription "for the end". The end of all struggles is victory as we have said above. Once we get a taste of victory, others against our enemies follow suit. In the first victory, where pleasures viciously contend against our life for the good of our souls, our inclination to the deceptions of the material realm has prevailed in favor of the good. Persons who pursue vanity and love what is false are condemned, but you have transformed your desires from visible reality to what is unseen."
On p. 72, St. Gregory writes: "The reason for the inscription, "For her who inherits" [Ps. 5] is clear. The soul has fallen from its own inheritance when the sun has set due to transgression of God's commandment. The prophet petitions God that the early morning might appear once darkness has past, and that we might be worthy of that sweet voice saying to those worthy of it, "Come, chosen of my Father, inherit the kingdom prepared for you from the foundation of the world" [Matthew 25:34].