The following is my view on this topic. It may not be correct but is what I believe from my studies.
God does for the most part not have a detailed plan for each person and he can't because of free will.
God's omnipotence and Omnisience is over rated and misrepresneted.
"God is the cause of all causes." is a quote from the Bible
God created the construct of the world. That it would have disease, famine, starvation, murder, births, deaths, love, anger and generosity.
Within all those mixture of hostile and benevolent forces which are randomly distributed and afflict random people (who god definitely does not personally handpick to afflict)
God is the cause of every person having cancer because he let their be medical illnesses in this world but randomness decides who actually gets cancer.
In terms of God having a plan for every one. He knows every decision you will make in your life and how your life will turn out from the very beginning. But that isn't because he has planned your life. Instead God is timeless. He is present in every moment in history and in the present and in the future right now as he sits outside of time observing time. He is the alpha and omega the beginning and the end. At the dawn of time he was already simultaneously at the end of time and is able to look back through all the events and all the free will decisions each human has made and will make. So he really does know all the decisions you will make before you will make them.
But you really do have free will and any path you pick will lead to a completely different life for the rest of your life. God both hopes you will and already knows whether you will pick him to follow but is resigned to it being your choice.
BUT WAIT it gets even more complex God does intercede and influence people's lives. Read the following quote of the interplay between God with your free will. Best read when smoking reefer in my opinion.
King James Bible
A man's heart deviseth his way: but the LORD directeth his steps.
New International Version
In their hearts humans plan their course, but the LORD establishes their steps.
BUT WAIT and then it gets ferrociously controversial when you discuss predestination
God hardens some people's hearts so that will never chose to follow him. Look at Romans
For those whom he foreknew he also predestined to be conformed to the image of his Son, in order that he might be the firstborn among many brothers. 30
And those whom he predestined he also called, and those whom he called he also justified, and those whom he justified he also glorified.
Want to move on to the next point you raised:
"Everything happens for a reason" is a secular saying and not biblical. So is "everything happens for the best".
Romans 8 28 is slightly different but similar to the above
28 And we know that in all things God works for the good of those who love him, who have been called according to his purpose.
Everything will workout for the best in other words if you love God and do something with good intentions. If you do something with bad intentions it will not work out for the best,
This final comment "It pretty sadistic if people are being set up to fail and then punished for it"
The majority of times if God sets someone up to fail it is so that they finally figure out that their system of problem solving doesn't work and that they should let the Lord be soveriegn in their life and follow his ways instead of using their usual decision making logic.
God also apparently has it in for proud and arrogant people and will make them fail as well
"God opposes the proud". "the meek shall inherit the earth".
You may know all of this already based on some of your earlier strong religious posts so sorry if all of this was a repeat info...