How is congregational prayer performed with one's wife, and does she stand beside her husband or behind him? And is the Sunnah prayer performed congregationally at home recited aloud?

If a woman prays behind a man, she stands behind him and not to his right. The proof for this is the hadith of Anas ibn Malik in Sahih Muslim, which describes the Prophet (peace and blessings be upon him) praying with Anas and the orphan in one row, and their old grandmother behind them. It is better for a man to pray the supererogatory (nafl) prayers at home individually. Congregational prayer for supererogatory prayers is disliked except occasionally, and it should be performed secretly if it is a daytime supererogatory prayer.