Would tenured professors who are charged with a crime generally be fired?

Criminal acts are certainly a reason to revoke tenure. In fact, this is probably one of the most common reasons. It is possible to terminate the employment of a tenured professor as soon as the university learns that they have been charged with or suspected of a criminal action. (This happened at my university: it was an extreme case.) Terminating employment because of a criminal charge is obviously a quite precipitous act to take: I would be surprised if a university did this in any situation except one in which they are sure that the faculty member will/would be found guilty of the charge. A tenured employee who was fired because of suspicion of criminal acts and was later found innocent of these acts would have, in many cases, a heck of a lawsuit against the university. (Untenured employees might as well...)

The things that "you heard" sound a little dopey to me, honestly. Tenure offers some measure of job security. It does not confer any defense against or immunity from criminal acts. Getting convicted of domestic violence is "something bad happening to the professor", right? Not being able to carry out your duties because you are incarcerated is a sufficient reason to fire a tenured faculty member! In the scenario with the "stalker" it is so unclear what happened or what was reported to whom that I would not be comfortable commenting on it. Nevertheless, one can certainly imagine circumstances in which a tenured faculty member could be fired for stalking even without a criminal conviction.

Yes, there have been. The case of Prof. Lasaga at Yale is one of the more egregious examples of malfeasance on the part of a faculty member, but also a case where the person stepped down well before being convicted (more background info here). I am sure that even though the language was of voluntary termination ("stepping down") that there was little choice for Lasaga otherwise. In lesser cases outside of the public eye, I am sure there are many professors who have also been asked to step down or to take an early retirement instead of being publicly fired.

Tenure only means our contracts don't have end-dates or renewal dates. It doesn't mean we cannot be fired for crimes, for being indicted for a crime, for other cause, or in some cases just simply being restructured out of our jobs due to the economic needs of our university.

Leon Shohet went to prison for some stuff he did with a federal grant, and U Wisc. didn't fire him; see http://www.wpri.org/WIInterest/Lueders8.1.pdf