Running It Twice and Insurance

[oldmangrimis]

I know what it mean and how to run it twice but what effect does it have on the outcome and why do players do it and how did it get started
InsuranceI have no clue what this mean, when to player are all in whatdoes it mean when one player offer another Insurance in poker
I can figger that he could be like BJ insurance but how do you fig out the odds each hand is diffrent

any help will be great