What is the opinion of the four madhhabs regarding how women pray in congregation, the position of the imam and the female congregants, and where a female worshipper stands when the last row is not full?

For women's congregational prayer led by one of them, the imam stands in the middle of the first row.

As for a worshiper joining the prayer when the row behind the imam is equally balanced on both sides, it is recommended for him to stand to the imam's right. If the left side is empty or closer, then it is preferable to stand there. The right side of the row is better than the left if they are close, but if the right side is far, then the left side and closeness to the imam are better.