If God didn't create evil and He's omniscient, it sounds like Satan was a surprise. Was God aware of how His praise worshiper would turn out? Please explain this.

God is also infinite with regard to knowledge. In other words, God is omniscient. He knows everything that has occurred in the past, everything that is occurring in the present, everything that will occur in the future, and everything that could, but will not, occur. In addition, He entertains no false beliefs, as He is cognitively perfect. He foreknew that Satan would rebel prior to (or apart from) Creation.

The advent of evil was no surprise to God. Although we might imagine that a world without Satan would be morally preferable, He permitted the Devil to rebel in order to demonstrate His glory to the world, just as He demonstrated His strength to Egypt, Israel, and the surrounding nations by permitting Pharaoh to flout his command to release Israel from slavery (Exodus 1–14). God reverses Satan’s schemes, so that “in all things God works for the good of those who love him, who have been called according to his purpose” (Rom. 8:28). For example, Joseph declared to his brothers concerning their betrayal, “You intended to harm me, but God intended it for good to accomplish what is now being done, the saving of many lives” (Gen. 50:20). God, unexpectedly, reveals the fullness of His greatness and goodness through the fall of Satan, which is our highest blessing.