Repentance from major sins

Q:

1. Would Allah accept salah of a person who commits major sins?

2. Would Allah accept salah of a person who gives and recieves interest (ribaa)?

3. Would Allah accept good deeds like salah of a person whose in debt?

4. Is it true if you miss 3 jummah(Friday salah) you lose your religion?

5. Does Allah accept repentance from a person who doesn't pray salah?

Mistakenly scratching someone's car

Q: What is the procedure in the following case:

I was at a parking lot. Just as I opened my car door, a strong wind blew it onto the car next to me and scratched the car abit and cracked the indicator light. I was scared and wasn't sure what to do. I considered leaving a note along with some money on the windscreen but I was afraid and drove away. Now it's really playing on my conscience. Please advise.

Superiority in lineage

Q:

1. My question is regarding the rule in Islam that commands Muslims to choose their caliph (khalifah) from among the tribe of Quraysh. The question here rises that how can Islam limit leadership to Quraysh and create a concept of Qurayshi , Non-Qurayshi.

2. Secondly I have read on another website that Arab Muslims who's piety is superior to non Arab Muslims piety in “general terms” as they are better in linage and descent. This again is a very irrational mentality. Clarify the following.