Maniy is pure and it is not essential to wash it from your clothes, but you must do Ghusl after it is emitted. Madhiy is impure and must be washed off if it gets onto the body. Madhiy invalidates Wudu' but it does not require Ghusl. Moisture is pure and it need not be washed off, but it invalidates Wudu'.

No scholar has said that breastfeeding a child is one of the things that invalidate wudu.

Bleeding from the nose does not break your Wudu according to the more correct of the two scholarly opinions.

The scholars agree that fainting is one of the things that invalidate wudu, even if it is brief. Whoever faints and loses consciousness, even for a moment, has broken his wudu.

If the sleep is light and the sleeper can feel it if he breaks his wudu, then sleeping does not break wudu whether the sleeper is lying down, sitting, leaning on something or sitting without leaning.