Re: They ALL mean Stop...
Technically red also means "Stop, unless it is unsafe to stop". All lights, signs and traffic rules always come with that proviso. You're never supposed to blindly obey a sign with no thought for what's happening around you, they're always saying what you should be doing unless there's a good reason to do something else. Exactly how good that reason needs to be varies - for an amber light simply not wanting to brake too hard is OK, while for a red light it needs to be something like getting out the way of an emergency vehicle - but it's always allowable to disobey road signs if it would be more dangerous to obey them.