There is a large misconception of "freewill". While it's true that we make choices, it is the Lord who determines the results. Those who suggest otehrwise would seek to limit God's utter sovereignty over His creation. I can will myself to be rich, I can will myself to be taller, I can will myself to have a nicer car. Those things that I will may or may not play out the way I want them to,
Pro 16:9 The heart of man plans his way, but the LORD establishes his steps.
But I take comfort in the LORD'S providencial care of me,
Rom 8:28 And we know that for those who love God all things work together for good, for those who are called according to his purpose.
So, regarding Free Will and heaven:
To the regenerate Christian, there is one driving force - to serve God and to live by His precepts and Laws. Our goal is heaven, where we can finally be made perfect in His sight, and spend our days worshipping Him in all His glory and majesty. We are made holy and righteous, we will have no other "will".
This whole notion of "free will" is man-made, as the unsaved doens't want anything to do with God or His law. "Free will" is a way that man attempts to excuse away fleshly desires, and seeks to say that God is not sovereign over their lives. Our inherent nature is sin, naturally our will is set against doing what He commands of us. This notion of "free will" is how many assuage their own guilt, rahter than repenting before the Lord and committing their lives to Him.
>>Do people make mistakes in heaven?<<
No. Silly to the point of being blasphemous. Heaven is perfection.