If so, why?
Because even the elect commit sins using their free will to sin or not to sin and we need to repent. Repentance is an act whereby we acknowledge we can not justify or set ourselves right with God through our own merit. We need the blood and grace of the Lord Jesus Christ. Jesus calls us to repent.
Yes, because it is part of the cleaning process. Turning away from our sin is good and He is a Gracious God to cleans us from all unrighteousness as we do.
Predestination does not absolve us from our duties the Word of God. But it makes it easier since He is so loving and kind towards folks like us.