1-Is my wife's maternal uncle her mahram? And may Allah reward you.

The husband's maternal uncle is not a mahram to his wife. The mahram relatives of a woman are clarified in the verse where Allah, the Almighty, says: (And let them not display their adornment except what appears thereof. And let them draw their headcovers over their bosoms. And let them not display their adornment except to their husbands, or their fathers, or their husbands' fathers, or their sons, or their husbands' sons, or their brothers, or their brothers' sons, or their sisters' sons) [An-Nur: 31]. What is forbidden by lineage is also forbidden by suckling.