Obviously not every vote is unanimous, but they are more often than not. And yes, they decide the order to read them and occassionally, don't read one that was different (though that happens rarely), but at the end of every episode, they do show all of the votes, so even though the cast doesn't know who the other votes were for, the viewers do.
Comments on last night - Tyson is very observant and good at thinking about what he might do in the same circumstances. This is the first time Brendan has chosen Stephen for exile. In fact, the first time Stephen has been to exile, and Tyson is concerned about an alliance with the other tribe.
And if they hadn't won immunity last night, it sure seemed like Brenden would have been voted off. I think a big part of the problem is that Brenden and Sierra are too close-knit. One of the first things said when they decided to vote off Brenden was, "We can't tell Sierra". I think Taj is actually smarter about this than Brenden. She intentionally chose Stephen and is keeping relations with him to a minimum so that no one thinks they are aligned. After all, what good is having the idol if you don't have someone who can warn you that you need to use it.
Of course, as seen last night, that can backfire. Stephen didn't end up having to make the choice, but it's very interesting that he was contemplating just keeping the idol and letting Taj take the hit.
Not sure what Jeff expects JT to do with his tooth...I guess keep it as a momento?