How can we have free will if God has a plan for our lives and knows everything we'll do in advance?
Since God is omniscient, God has foreknowledge, meaning he knows what everyone will do in the future and what any individual would do in any given situation. This foreknowledge enables God to have a plan for everyone's life. For instance, if God wants a particular action to occur, he knows who would choose to do that action, and under what circumstances they would choose it; thus he is able to plan for it to happen. However, God's knowing what choices we will make is simply knowledge - it doesn't remove our free will, for we are still the ones making the choices.
This may be more understandable if we consider that we have a type of foreknowledge from our knowledge of history. For example, we know that the Americans won the Revolutionary War. If we went back in time before the Revolutionary War took place, our knowing the outcome wouldn't force anyone to do anything. Our knowing the Boston Tea Party would take place wouldn't mean that the colonists would be forced to throw the tea overboard, it would only mean that we'd know what the colonists would choose to do. It's the same with God: his knowing what we'll freely choose to do doesn't mean we're forced to make that choice.