Serendipity

Serendipity: a fortunate accident. Tied with destiny and fate - but sort of like a sub-branch of the two. I know it's supposed to be a feeling you get when it happens to you, but I can't help thinking:
Does serendipity have rules?
Because the way I see it, luck doesn't have any rules - it's just luck - but maybe serendipity could. Ah, the possibilities!
1. Does serendipity happen to everyone? Or a select few?
2. If 1 = yes, then do people get multiple serendipities? Or is it just, like, one per lifetime?
3. Do you have to deserve a serendipity?
4. What are serendipities for? Finding your soul mate? Figuring out your goal in life? Generally the different aspects of destiny?
5.  Does it happen only to the people to need help finding the aforementioned?
6. Is it random?
7. Can it happen if you try to find it? Or does it happen only when it's unexpected, like the wardrobe leading you to Narnia?
8. Could serendipities have a scale of seriousness? For example, a 1 on the scale would be happening upon your lost iPod by chance . . . 10 would be help with something that affects your whole life in a very positive way.
9. Is serendipity like a push when you need something to tip the scales, when you're struggling? Or can a simple act of serendipity do all the work?
10. Is serendipity even common enough to answer all these questions? Or is it just a rare set of circumstance?