I'm not trying to re-invent the wheel so these are some tidbits that came up in scattered places in addition to the apologetics texts (see sidebar for my apologetics shelf) that I'm finding extremely helpful.
Regarding Catholic doctrine on the Eucharist:
John 6:51-68 is particular striking.
I am the living bread that came down from heaven; whoever eats this bread will live forever; and the bread that I will give is my flesh for the life of the world." (John 6:51)Unabridged Christianity by Fr. Mario Romero (Queenship Publishing) has a terrific exposition of this segment. Isn't it interesting that the miracle of the loves and fishes begins this teaching takes place in the context of the Jewish passover?
A few quotes on the Blessed Sacrament:
Saint Claude de la Colombiere:
It matters very little if you approach the Sacraments with sensible fervor, provided that you replace this with deep and sincere humility. Without this humility there is nothing more despicable in God's eyes than ourselves, but with it we can go to him without fear, certain that he will deign to look on us with infinite mercy (The Spiritual Direction of Saint Claude de la Colombiere translated and arranged by Mother M. Philip, I.B.V.M. - Ignatius Press)J.R.R. Tolkien:
Out of the darkness of my life, so much frustrated, I put before you the one great thing to love on earth: the Blessed Sacrament. . . . There you will find romance, glory, honor, fidelity, and the true way of all your loves on earth, and more than that. (from a letter to his son - Letters of J.R.R. Tolkien, Houghton Mifflin)Fr. Ronald Knox:
Saints of the Eucharist includes many more beautiful quotes.
The Blessed Sacrament is the sacrament of unity; and when you receive it, it does not merely produce in you more charity towards your neighbour, more loyalty towards the Church, more unselfishness in your human attachments. It makes you more at unity with yourself. (Pastoral and Occasional Sermons - this gorgeous book is on sale for half price currently at Ignatius Press and includes a large segment devoted to sermons on the Eucharist)
Reception of Holy Communion by non-Catholics
Dr. Gotcher pointed me to this site which details who can and cannot receive Holy Communion.