A very large majority of them do. Their group is unlike Republicans and Democrats. Their difference is that they are a group of extremists, therefore all Tea Partiers are extremist. If there are some that arent extremist than they're not very bright as they can basically vote republican for all the same things minus the extremism and getting labeled as an extremist nutcase.
Not quite. You see, the political system in Norway has a similar party, with similar views (although they often have different reasons for these). They are vastly unpopular in the media, and also among the other parties, but they are the third largest, and not at all far behind the other parties. Why is this? Because the views that get picked on by the media are what central figures have said, and not what the main bulk of them support these views. There is a similar situation in Sweden - there were news in major outlets about Sverigedemokratarna getting great results in elections, despite the fact that everybody ostensibly hates them.
The same is true for the Tea Party. You do not join a grouping because you share all their ideas, but because they front a case that you agree with. Some, of course, are well-reflected in their choices. But the majority, and this goes for every single political movement on the globe, are part of it or support it because of one or two main causes that their party are promising to deal with, even if these are merely nuances in detail. Or they join because they are jaded with or disagree with central ideas among the opposition. Those who are represented in the media are seldom to never representative of the majority or the plenum, since the news outlets want shock value and headlines that sell.
The Tea Party is not as extremist as you make it out to be - the most known among them are, of course, but not the macro. Rather, they are common people who made a choice, one that might be dumb (but not evil, or warranting of the "stupid"/"extremist" label), but a choice nonetheless.