You did answer well when you said that Noah preached righteousness by living a life pleasing to God, specifically by acting in faith and acting on what God instructed him to do. His lifestyle, his actions where a demonstration of righteousness. Many preach righteousness, but very few live it. We are to become living epistles, living walking billboards of the Lord Jesus Christ. God wants His Word to Become flesh within us.
My observations regarding the scriptures in 1 and 2Pet regarding Noah are these. Noah believed and acted on God's word. By believing and acting upon God's Word Noah showed himself to be righteous, and as a result brought the flood upon the earth. In other words his obedience to God's Word put God's Word in action and brought the flood. This begs the question, if Noah did not believe and act upon God's Word, and thus did not show himself to be righteous in God's sight, would the flood have come? I strongly suspect not. If Noah did not act in obedience, and thus did not show himself righteous in God's sight, If God sent the flood all flesh would have perished, and God's own prophecy in Genesis 3 would not be fulfilled, then God would appear to be a false prophet. But we know and are fully assured that God's word is yea and amen, it does not return void but fullfills all that it was sent to accomplish.
God Bless you my Brother, and may He who is The Lord Of Glory, the Firstborn from among the dead, He who was dead but is alive forevermore and in whom is light and life, cover keep and preserve you and yours.
Hoplon