dude you are sick

hello friend iwould like to correspond with u as ur pal friendship by exchanges email and snail hope to hear from u soon

That sentence doesnt make any sense

Sorry, I can't explain that sentence without the context it is in.

What came first, the chicken or the egg?

"foundation" would be a better word than "underneath" here. The "tortoises all the way down" is another way of saying that there's no ultimate basis for knowledge.

If you mean "real estate leads" I think it's american english for the possibility of a sale for people who work in real estate, which is buying and selling property. A "lead" is a potential opportunity or customer.

Sorry, I have no idea what that is

You're on your own for that one.