What is the ruling on passing wind during prayer after performing ablution (wudu')? And what should I do if I performed ablution and entered the restroom before prayer but did not defecate? And is it obligatory to enter the restroom before every prayer?

The matter is clear and presents no difficulty. If you know that the wind stops for a period sufficient for purification and prayer, then wait, perform ablution, and pray. If you do not know, then you may perform ablution after the time for prayer begins and pray the obligatory and supererogatory prayers with this ablution until the time expires, and whatever exits from you will not harm you. You must strive against intrusive thoughts (waswas) and not pay attention to them.