Is the Imam required to ask for the straightening of the rows behind him when he is not in the middle of the worshippers, and what should he do if the two sides of the row are not straight?

It is best for the Imam to be in the center, whether in the mosque or elsewhere. If the row behind the Imam is even, it is recommended for the worshipper to stand to his right, due to the hadith of Al-Bara' bin 'Azib: "When we prayed behind the Messenger of Allah, may Allah bless him and grant him peace, we loved to be on his right so that he would turn his face towards us." The Imam should encourage people to stand centered around him.