Using interest money to pay tax

Q: As per new Saudi rules, they are charging many levy, taxes, even charges of exit/entry and iqama charges. My father have 7 dependents under him which and we are paying government more than 40,000 riyal from our halal earned money. In this case, is it possible to pay them by depositing our money in fixed deposits and give them interest amount and get rid of it? 

Marrying one's first cousin

Q: I'm really worried and need advice on the matter of first cousin marriages.

1. What is the Islamic view on the matter? Should I be worried about the research online which says the chances of having a kid born with some kind of disability increases with first cousin marriages.

2. Could you please give me famous examples, specifically of first cousin marriages in Islam. Did Nabi (sallallahu alaihi wasallam) marry his first cousin? Was Ali's (radhiyallahu anhu) marriage with Fatima his first cousin?

Accepting literature of different religions

Q: I live in the west, and every now and then, some Christian or Jew knocks on the door to give out pamphlets that promote their religion or an event related to their religion. I normally refuse the pamphlet but sometimes they put it in my hand, in which case I say ok and throw it out after I close the door. The people who give this stuff to me know I am a Muslim as I wear the niqab. Does my taking the pamphlet constitute kufr? Am I obliged to refute their religion to them right then and there at the door? If I don't, is that kufr?