3:13 One of the key words in this passage is "Wisdom," or in Greek "Sophia." Before getting to the meat of the word, we have a nice look at the genetive here. The end of this verse says, "in gentleness [genetive: wisdom]." The NET translates this "gentleness that wisdom brings." The NRSV gives "born of wisdom" and the NIV puts it as "from wisdom." This is one case where the later context (3:17) gives some help.
Also, another Greek note. In verse 13, we have the Greek phrase, "en hymin" which means, literally "in you" but is really "among you all." Often times the Bible translates this phrase as in "in you" (like in 1 John, the love of God in you) when it should be translated, as it is here, among you all.
3:14 The Greek subjunctive clause here strengthens James' point. He does not simply say, "If you have bitterness..."; he puts this a bit more strongly, "Since you have bitterness..." The resulting "mh" (negative clause) with a present indicative verb means that the action occuring (in this case, lying) is on-going. In other words, I would translate this, "You have bitter envy; stop lying!"
3:15 The word in 3:15 for "unspiritual" is an odd one -- psychicos, which clearly has its origins in the idea of the "soul." At some point, this word became the opposite of "pneuma..." The Latin translation of this word is animalis. I don't know what to make of this, but I thought it odd!
3:16 There is a great word in this verse: "akatastasis" which means disorder; in Acts 3:21, Jesus is said to be the apokatastasis!
3:17 The wisdom from above (again anwthen, used in John 3) is first holy. Well, let's just stick Jesus in there. The wisdom from above is first Christ. Then it is...
But getting back to the genitive in 3:13, we see that the proper (holy) widsom produces gentleness, not the other way around. So the earlier genitive is a genitive of origin/source: the gentleness from or begun in wisdom.
3:18 Here we have a great look at the dative. The expression is the substantive participle, "those who make peace." The question is, what is the role of this in the sentence? It is in the dative; no prepositions given. The "fruit/harvest of righteousness" is the subject; the verb is "sown"; "in peace" seems like an adverbial phrase for the verb. So, the part that everyone agrees on is "The fruit of righteousness is sown in peace..." But what about the peacemakers? The NET takes this dative to mean location, as in "the fruit sown among those who make peace." The NRSV looks at the dative here as an indirect object, "for those who make peace." The NIV, on the otherhand, looks at the dative here as the object of means, "by those who make peace," and then takes the sentence and makes it active (Those who make peace sow..."
4:1 The words James uses to describe the situation have military overtones; conflicts is "polemos" (like modern polemics) and "machai" which means is akin to the word for sword (machaira).
4:1 The word for "cravings" is "hedone" as in "hedonism."
4:8 The Greek here is not set up as a conditional. Draw near to God and he will draw close to you not connected through any if-then clauses (and Greek has a million ways to do this). Given the relational langauge found elsewhere in this section, I wonder if you could look at this verse (and the previous verse) this way: Leave the devil; He is fleeing because of Christ. Go home to God; for he is also on the way.