Lobster Questions

I love to eat lobster. I never would order it in restaurants, because of its expense; but then I moved to New Hampshire where there was a ready supply of it, and just went crazy. Ever since then I've loved lobster, although I'm back to scarcely ever eating it. But here's what I just don't understand about lobster: how on Earth did people decide it was something to eat?

As far as I know, lobsters live at the bottom of the sea, and don't generally walk up to shore. Occasionally, I would imagine, a dead one would wash up; but I've been told that dead lobsters are inedible, that they have to be cooked live or very recently killed, or else they make people ill. I'd love to have been a fly on the wall at the eating of the very first lobster, because I don't know many people who would see a dead lobster, watch their friend get sick eating it, then go seek out live ones at the bottom of the ocean to see if eating them would not make them sick. You'd have to be pretty damn hungry to go that far after something that looked like a giant bug.