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?

Using interest money to pay import duties

Q: Can interest money be used to pay the import duty, taxes, anti-dumping (AD), and countervailing duties (CVD) which a government levies on imported goods?

Anti-Dumping Duties (AD): "A protectionist tariff that a domestic government imposes on foreign imports that it believes are priced below fair market value...They come into play when a foreign company is selling an item significantly below the price at which it is being produced. The logic behind anti-dumping duties is to save domestic jobs, although critics argue that this leads to higher prices for domestic consumers and reduces the competitiveness of domestic companies producing similar goods." [http://www.investopedia.com/terms/a/anti-dumping-duty.asp#ixzz3ZkRuXZqq]

Countervailing Duties (CVD): Countervailing duties (CVDs), also known as anti-subsidy duties, are trade import duties imposed under World Trade Organization (WTO) rules to neutralize the negative effects of subsidies. They are imposed after an investigation finds that a foreign country subsidizes its exports, injuring domestic producers in the importing country." [http://en.wikipedia.org/wiki/Countervailing_duties]