Changing one's gender

Q: I have a question. My brother who was before while he was a baby/born was a girl. After that s/he was being checked up at the age of 16-17 because s/he didn't have period like any normal girls. After they checked up they've found that his real gender is a MALE. So s/he decided to make an operation to be a MALE (his real gender).

Dirt around the private part

Q: Dirt is formed due to sweat around my private part (black dirt) and gets stuck near the place where the circumcision begins (and this dirt can only be seen if there is an erection). Recently it occurred to me that this might have prevented the water to reach the skin during ghusl. I don't know whether that dirt is porous or not. Was my ghusl valid which I have been doing the same way without noticing it from the day I became baaligh. If ghusl is not valid, are my clothes and the towel and all the other things which I use everyday are they paak?

Giving zakaat to one's nieces and nephews

Q: My sister and the former husband abandoned three kids and are now cared for by my parents. They have grown and are on the brink of their teenage years. My parents who have cared for them have now almost retired. I help where I can but is not always able to help fully. I have zakaah due to be paid in the coming month. My questions are:

1. Can I pay zakaah to my parents to cover for their (nieces and nephew) needs?

2. If so, can I give all my zakaah to them or only a portion.

Learning Arabic

Q: What is the best way to learn Arabic language? Can I learn it myself or I have to learn it under the supervision of some scholar? I have an Arabic grammar book which is in urdu, my urdu is good so I found it really easy to understand. Can I learn Arabic myself and ask things which I don't understand from some scholar?