How does the PoS stake work?  Some questions...

1)  How much time do you need to contribute to receive stakes?  How often are stakes paid out? 

2)  What is the typical stake size?  Does having a larger wallet increase the size of the stake you receive?

3)  What happens if you close your wallet overnight, then re-open?  Is your network time contribution saved or does it reset each time you open/close/re-open the wallet?