Judges 5 is a familiar scene that we've seen before in the Bible, and we'll see again: Battle's over, and having won, the Israelites sing a victory song. Typical of this sort of thing, there's a lot of poetic language, some of which (such as fighting "stars") the SAB picks up on and criticizes, and some of which (such as God himself marching into battle) it does not. Anyway, my blanket response to most issues here is that this, being a piece of poetry, is not expected to be realistic nor completely accurate. Not that there is nothing that can be said beyond that.
So when God's marching into battle and mountains are melting, you might suspect that we're being figurative, but many of these figures of speech have some meaning behind them. Basically, most of what is going on here is a description of the idea that God was on the side of the Israelites, and therefore nothing could stand against them. This imagery could be the meaning of the claim that the stars fought against their enemies: the idea that when God is on your side, essentially all of nature is fighting for you. There may be another sense in which this is more literally true, however. It is common in the Bible for "stars" to be a metaphor for "angels", which answers a lot of questions. It may be in this case that they are claiming the battle was won with the help of angelic beings, which I know to some isn't much of an improvement, but it makes more sense than the idea of the battle being fought by flaming balls of nuclear plasma in space.
The song talks about Jael, and brings up the real issues that I addressed briefly in my last post. Jael is praised for murder here, and it seems odd, yet this was in the middle of a war. If Osama bin Laden were on the run from the marines and asked you to hide him, don't you think you'd at least consider killing him? Dying instantly in his sleep might be considered a mercy, as based on other cases where enemies were captured alive, you'd think much worse could have been in store for him.
Verse 30 may be a misreading on the SAB's part, but as in a few other places, it's hard to tell, as there is no commentary. The verse talks about dividing the spoils of war, including the conquered women. If you read it carefully in context, you realize that it is not a description of something that has happened, but a description of what the Canaanites imagine would happen if Sisera won.
The last verse presents two issues of a very different nature. First, the Israelites declare that they wish all the enemies of God would die. This does seem rather mean and intolerant, yes, but on top of other things I've said in the past about such topics, note that God Himself does not say that He wishes this, it's the Israelites saying these words, and for the umpteenth time, they're not exactly the apex of virtue.
Lastly, there is some poetic prose talking about "the sun...goeth forth in his might." Aside from being obviously (to me, anyway) more metaphorical, poetic speech, I think the SAB note is reading in something that is not there. The SAB says, "The sun, according to the bible, goes around the earth." This may be so, I have little doubt, but it does not say so here. There is nothing about where or how the sun "goeth forth", only an observation that it does so. And while I think it is not an issue here, it's as good a place as any to reiterate that even in today's culture, in which we know that the earth orbits the sun (which technically it doesn't) it's perfectly acceptable to say that "the sun rises in the east and sets in the west" even though, in fact, it is not the sun rising and setting, but the earth's horizon.