According to the quran the universe except for earth, at that point was vapor. that is not scientificaly true.
I don't really know, it depends how you interpret and understand the verses, its just says that stars were made at that point, it doesn't say all stars, nor does it say some stars, it just says stars.
However, we have to keep in mind that God is explaining his creation of the heaven and the earth, he is also representing it in some sort of timeline were he proceeds from one point of creation to the next one. the stars weren't mentioned anywhere before earth was created so that must be the point were he created them specially when he said that before that the universe was vapor, notice also that he said vapor, not 'only vapor', he also said the heavens, not all the heavens, so it depends how you want to understand it.
For me, I think that God is trying to be clear here on how everything came to existence, keep in mind that the surrah its self is called ''In detail'', it would be pointless to argue that these verses didn't mean that earth came first, or stars were there but he didn't mention them, for if that is true he would have rephrased and worded the verses differently.