To tackle the second question first:

In the introductory of post of his Opening Shots Project, Jim Emerson says:

Any good movie -- heck, even the occasional bad one -- teaches you how to watch it. And that lesson usually starts with the very first image.... The opening shot can tell us a lot about how to interpret what follows. It can even be the whole movie in miniature

I certainly admire the notion, though I'm not sure it applies quite so directly to books, if only because a picture's worth a thousand words, dontchaknow, and a moving one thus worth 30,000 per second.

The lines I think of off the top of my head are the obvious ones:

"Call me Ishmael"
"It was the best of times, it was the worst of times."
"A screaming comes across the sky."
"Lolita, light of my life, fire of my loins."
"Money...in a voice that rustled...."

Which seems partly a function of the degree of success with which they fulfill the "introducting the work" aspect, but also because they are short and pithy and thus easy to remember. In fact, other than the alliterative Nabokov, I'm not sure I can say that any of them hold much discrete value outside the context of the books that follow.

i'm 2 much for these niggas and 3 much for these hos