1). Why did Jesus model solitary prayer?
I believe it was a custom for Him to get alone with His Father in heaven. Jesus knew that He needed His Father's help, so He stay connected to His Father by getting alone with Him daily.
2). What is deep contemplation or reflection that will bring God's Word from the head to the heart?
Meditation is very beneficial spiritually, mentally, and physically; and I speak that from a personal experience. I have experienced praying all night and then when I get to a place of deep contemplation I can actually experience that place God desire us to be. Then, and only then we can read His Word and get spiritual revelation.
3). In Jacob time alone with God, (Genesis 32:13-28) the angel said Jacob prevailed; Explain what the angel meant.
He did not give up. He stayed before God. He refused to let go. He had spiritual power, and if we want that we need to get before God and stay there until the breakthrough. Honor God by giving Him our time alone.