Homosexual marriage should be equivalent to heterosexual marriage in every respect.

"Should be" doesn't mean that it is.

If women can have equal rights in the modern world then in the eyes of the law, man and woman are the same.

This is where the problem begins. The notion of "Men and women are equal" is not true. There is huge difference between the genders. On average, women will never make good soldiers and men will never be good care givers. The rights should be accorded to a persons abilities.

Again, I have read about plenty of normal parents being abusive to their children.

Yes, there will always be exceptions and there will be exceptions on the other side too, some gay/lesbian people may bring up excellent children. There is a very important point which OP raised, "child’s best interests". Marriage according to Hindu traditions should always be about serving the other person and not for the purposes of consumption(it can be emotional, physical, etc)

Can I be any more clearer than this in how ridiculous it is to suggest that homosexuals are somehow mentally broken people? Are you bat-shit crazy?

I think that OP just wanted to say that homosexuals are different and "illness" is not a good word to describe the difference.

It is all about recognizing who is good at doing what job and then giving them the right to perform that job. That is how it works everywhere. A gay couple will never be able to provide food to an infant. A natural mother is a walking kitchen for an infant. A natural mother is MORE LIKELY to take good care of the infant.

The idealistic notion of equality doesn't hold in reality, people are not equal.