Does bleeding from the body, such as from wounds, invalidate ablution?

Bleeding doesn't invalidate person's ablution. And Allah Knows Best.

I`m getting old and haven`t got married yet. I love wearing the veil, but people advised me to take it off because it could stand in the way of my marriage, and that I should wear it after getting married, what should I do?

The veil (face drape) is the wear of the Prophet`s (PBUH) wives and righteous female companions (May Allah be pleased with them) and whoever imitates a certain group of people shall receive the same reward or punishment like themselves. Only those who are religiously poor deny women wearing the veil, and thinking that it stops a woman from getting married is from the evil suggestions of the devil.

Is it permissible for a woman in her waiting period (Iddah) after her husband's death to leave her house and mix with non-Mahrams?

It is not permissible for a woman in her waiting period (Iddah) after the death of her husband to leave her house except for a necessity, such as for medical treatment, nor is she allowed to mix with non-Mahrams. A woman is not permitted to mix with anyone other than her husband or Mahrams, whether she is in her waiting period or not. However, there is no harm in accepting condolences from those who visit and responding to their inquiries about her well-being. And Allah Knows Best.

After our father had passed away, my brother and I stayed with our mother for twenty years and served her to the best of our effort. However, she asked our other brothers (3) to support her financially but they refused to pay her anything. As a result, she gave her share of the inheritance to me and my brother. What is the ruling of Sharia on this?