Purity

The majority of scholars say it is mandatory! However, the most authentic opinion is that it is highly recommended

Of course.

One must perform wudhu if it is not sufficient to perform ghusul with that water.

Only over your hair  forward  and backward on the top only and not the scalp.

True, if the ankle is revealed.As long as the ankle is covered there is no problem.

Any emission from the private parts breaks the wudu. As long as nothing has been emitted, the wudu isn’t broken. Itchiness does not break wudu.

This is permissible.

Wudu expiates sins and keep away the evil “When the Muslim or believing slave does wudu and washes his face, every wrong thing that he looked at with his eyes comes out from his face with the water or with the last drop of water. When he washes his hands, every wrong thing that he […]

If you washed it properly then you can pray in it even if there is a color.