To really get what Paul is saying you need to start in Romans 5 and read from there.... in fact you could start back at chapter 3... but it all gets so much you may get a bit overwhelemed if this is your first tackle of this material. Paul packs so much theology into these few chapters and Romans 8 is the ending of a long discussion.

The bottom line of it is this:
Jesus took all your sin at the cross. You are united with Jesus in water baptism and receiving of the Holy Spirit. There is still a battle going on between your sinful nature and the new man you are in Christ. The way to let the new man have victory over the sinful man is to be lead of the Holy Spirit. He will take you into relationship with the Abba Father...(Daddy) and in that relationship there is no law or condemnation only victory.

You ask: "Am I free from Sin and Death even though I walk according to the flesh?"
The answer just from Romans 8 alone is a) you don't walk according to the flesh if the Spirit of Christ is in you (verse 9) and b) Jesus set you free from the law of Sin and Death by what He did (verse 3-4).
Jesus opened a door for us to recieve the Holy Spirit of God. When we have this Spirit we are no longer "in the flesh"... when we are "lead by this Spirit" then we overcome sin.

Keep wrestling with these Scriptures bro.. there is so much in them that is good.

Blessings
Cat.