Question about Yeltsin and Putin

What made Yeltsin just give up his position and hand it over to Putin? Why was Putin the only one chosen? How come Russia didn't just run an election? Did Putin blackmail Yeltsin? I mean there has to be more to Putin then some President just stepping down and giving his seat away to the head of the FSB (KGB) organization. What did Putin have over Yeltsin head to make him step down abruptly? Or, was it because of his health issues?

Thanks.

Just needs some insight.

With Putin passing his new law last week, why does it seem like he's some secret Stalin?