Sword of the Spirit

At camp a few weeks ago our whole group learned the armor of God verses from Ephesians 6. As a counselor, I was working with the junior high girls to learn and understand their verses. (Praise for teamwork; other people were on the job, too, including the 'Bible hour' teacher and some of the other staff and counselors.) The language of the Bible is sometimes more grammatically complex than everyday usage, so breaking the verses down phrase by phrase and discussing the meaning can help the kids keep the verses in their heads and hearts, as well as legitimizing their inflection. So I was helping one of the girls with verse 17: "And take the helmet of salvation, and the sword of the Spirit, which is the word of God:" and started explaining the sword of the spirit part. I don't even remember what I told her, but I know that since that day I have been trying to figure out what it means.

A few questions:
How significant is the comma after "salvation"? Since "take" is not repeated, are we to equate the term "helmet of salvation" with the term "sword of the spirit"? Or is there any way to "take" one without the other?

Does the sword belong to the spirit, depend on the spirit, or consist of the spirit? Cross references usually lead to Hebrews 4:12, whose subject is also the word of God, which seems to cut things, including soul from spirit. But the Greek for "word" is different in Ephesians from Hebrews.

Back from camp, catching up with a friend, she reported that her small group is going through Ephesians, and that one of the teachers was excited to get to the armor of God and the sword Jesus uses to kill the wicked. (See Revelation 19:15, 21) Is that the image here? Earlier in Revelation the sword seemed to be more of a tool for discipline, discerning the spirits of the churches. The Revelation sword proceeds from the mouth of Jesus.

Is spirit supposed to be capitalized? Are we talking about the Holy Spirit, my spirit, or things spiritual? Or should the sword be used against the spirit?

When Paul says, "which is the word of God," is the antecedent the sword or the spirit?

I looked up the Greek for this verse. My use for Greek extends to definitions, but I'm helpless when I come to grammar and tenses. But I did notice that the Greek for "word" is an utterance, not something written (in the Greek, rhema). Usually I hear teachers explaining the sword of the spirit and (ignoring that little phrase, 'of the spirit') holding a Bible above their heads telling their students that they have to know the word of God, and to study it, to use it like Jesus did when he was tempted in the wilderness. Except the next thing teachers say is that the sword is the offensive weapon in the armor list (some add prayer, from verse 18). I don't see how resisting temptation is an offensive act in the spiritual war we're fighting.

So what is "word of God"? Are we talking about words God has spoken, or words God is speaking? Ephesians 6:19 includes Paul's prayer request that words (different Greek than verse 17: here it is logos) be given him. Given him? By whom? Whose words are they if they were given? What did Paul want to do with words? This is one of the first times in this whole article where the biblical context answers the question, because Paul says he wants to use the words to preach the gospel boldly (which seems rather offensive).

Finally, verse 18, about prayer, rather than being a new sentence, is presented as a continuation of the thought in verse 17. But what does prayer have to do with the "word of God" or "sword of the spirit"?

How exactly ought we to apply this verse, then?

To God be all glory.