You have a problem in the concept of omniscience. Omniscience means knowing all that is knowable. If you have free will, what you will do in any given circumstance is not necessarily knowable to a certainty. Omniscience is knowing to a certainty that which is knowable.
It is the same with omnipotence. Can god make a rock so heavy that he/she can't lift it? That's just a paradox of language; not doable.
All these linguistic paradoxes are actually the outlines of our reality. God's reality maybe a superset of our own.
BTW, I don't much believe... God can think and choose what he/she wants. Thank God (or whatever) I can think and choose what I want.
P.S. God can't make a square-circle either. It doesn't make God less than omnipotent. Since God probably doesn't exist, it probably makes no difference.
Love may laugh at locksmiths, but he has a profound respect for money bags. -- Sidney Paternoster, "The Folly of the Wise"