Does doubt about remembering the intention for prayer after waking up, and about completing the ablution, and about the number of rak'ahs affect the validity of the prayer, and does sin result from that?

The cure for obsessive thoughts is to ignore them and pay them no mind. No matter how many obsessive thoughts come, you must repel them. If Satan instills obsessive thoughts about ablution (wudu'), or the number of prostrations (sujud) or cycles of prayer (rak'at), then banish these doubts and build upon what you have completed. If you wake up at the very end of the prayer time, perform ablution and pray; there is no sin upon you even if the time expires while you are praying or before it, because the sleeper and the forgetful person are not held accountable. Do this in all your affairs until Allah grants you well-being.