Mezuzah in an Apartment

You may have seen the story about the new statute in Texas allowing tenants to put mezuzot on their exterior doorways. Apparently, this was in reaction to a situation where a resident was prohibited from putting up a mezuzah by the rules of his apartment community. I was curious what Jewish law would have said about this situation. If a Jew finds himself living in an apartment complex that prohibits hanging anything in doorways, what is he supposed to do? Defy the ban and hang a mezuzah anyway? Move and incur substantial inconvenience, costs, and possibly lease violation penalties? Or do the property rights of the apartment complex owner simply override the biblical commandment?

Mezuzah on a Car?

I noticed a number of ads on the Internet advertising mezuzot for cars. It would seem that if a mezuzah is a symbol of one’s Judaism, one’s car would be as much a place to put a symbol as a home, but it just seems kind of strange. Is there a mitzvah to attach a mezuzah to a car?

Mezuzah

I’ve been wondering about the Hebrew letter shin on the Mezuzah cover. Could you please fill me in on its significance?