As for Chapter 8, Doug Moo says it well in his brief commentary on Romans contained in the New Bible Commentary--
"The Christian’s deliverance from condemnation—the penalty of death because of sin under which all people live—takes place by virtue of our union with Christ (5:12–21). Vs 2–4 (of chapter 8) explain further that this deliverance has been accomplished by the triune God: the Father sending the Son as a sin offering for us (3), on the basis of which the Spirit liberates us from the power of sin and death (2) and secures complete fulfilment of the law on our behalf (4)."
Moo goes on to state:
"Through Christ Jesus the Spirit of God sets us free from the situation of bondage to sin and death alluded to in 5:12–21 and 6:1–23 and described in 7:7–25. The Spirit must so act because the great power of the ‘old regime’, the Mosaic law, was quite incapable, because of human weakness, of breaking sin’s bondage (3a; cf. 7:14–25). What the law could not do, God did: he broke sin’s power—condemned sin—by sending his Son to identify with us and to give himself as a sin offering...[t]his sending of the Son enables the true fulfilment of the law by those who live according to the Spirit. Paul does not mean that Christians are enabled to obey the law (however true this might be) but that Christians are considered by God to have fully met the law’s demand because of Christ’s obedience on our behalf."
Moo goes on to perfectly outline the doctrine of adoption found in verses 14-17. Paul illustrates that being "in Christ" not only frees us from a death sentence but also brings us into such a close relationship with God that we are virtually His adopted children BUT as His children we are also heirs with certain family responsibilities including joining the suffering that will eventually make God's good creation perfect again. Paul finishes the chapter assuring us that although those of us in Christ will indeed face great suffering, we need not doubt our ultimate salvation because we have been chosen by God even before the beginning of the world. This sets the stage for the controversial but powerful argument of election outlined in Chapter 9. Check back!
