Question #1: How does God's providence work? Does he really have a plan already in place for me? How do my free will choices factor into this?
The interaction between God's sovereign work and human free will is a logic "problem" that has been analyzed by some of history's greatest thinkers. Scripture consistently affirms the reality of both God's predetermined plan (e.g. Jer. 1:5, Ac 17:26) and humankind's ongoing free moral agency (e.g. Dt 30:19-20, 2 Pt 3:9). The implications of our conclusions have wide ranging effects in how we understand our individual salvation. It's helpful to notice the difference between God's foreknowledge and predestination. For example, David asked God, "Will Saul come down” and the Lord answered, "He will." So David and his men kept moving from place to place, and when Saul heard David had escaped, he didn't go where God said he would (1 Sam. 23:8-29). Was God wrong? No, God was giving David the conditional answer he needed, and what actually happened was shaped by David's choice to leave. If God predestined this, Saul would've gone down anyway. In other words, God knows—not only what we will do—but what we would do in any possible situation. In this way, He can shape events to bring about his plans while leaving our choice to us.
Like the Pharisees, many have "rejected the purpose of God for themselves" (Lk 7:30), but God will succeed in the end, since he "has made everything for its purpose, even the wicked for the day of trouble" (Prov.16:4). It is our job to "work out your own salvation with fear and trembling, for it is God who works in you, both to will and to work for his good pleasure" (Phil 2:12-13). David declared how God knit him together in the womb (Ps. 139:13), adding "in your book were written, every one of them, the days that were formed for me, when as yet there was none of them" (139:16). When we strive to fulfill God's purpose for our lives, it shapes our attitudes and actions in ways that God can use. Imagine how history would be different if Joseph looked at the events of his life and said to his brothers, "you meant this for evil, and now I can get revenge." Instead, he chose to look at those events and see the hand of God, leading him to say, "you meant this for evil but God meant it for good" (Gen 50:20). Because of this choice, the tribes of Israel (including Judah, from whom our Lord was descended) were preserved and God set the stage for the great Exodus. The point isn't Joseph's special purpose, but rather yielding to God's will. That's His aim for everyone.