These are good questions. I do not think anyone knows exactly, but I have heard the conjecture often that Pluto is an escaped moon or a captured planet from somewhere else, and was not present at the formation of the Solar System. Also it is possible that Pluto's strange orbit is the result of some collision.
The rotational angular momentum of Uranus is quite different from the other planets. It's rotational axis is tilted significantly from the orthogonal to the ecliptic (plane of orbits of most planets), and it is said to rotate in the "opposite" sense to earth and the sun and some of the other planets. However, since the tilt of Uranus' rotational axis is roughly 97.92 degrees, I do not know how strongly I would want to assert that it rotates in the opposite or retrograde sense to most of the other bodies in the solar system. Again, this could be caused by a collision. In one of the attached references, it is claimed that this could be caused by a tidal effect, but it is hard for me to understand how.
It turns out that both Pluto and Venus also rotate in a retrograde sense, so it is not that uncommon, although theories of the origin of the solar system imply that one would not expect a lot of deviations of angular momentum from the major direction of angular momentum in the system. In the case of our system, especially given the orbits of the planets with small inclinations to the ecliptic, and the very large angular momenta of the Sun, Jupiter and Saturn, this is basically correct.
Neptune is probably called the blue planet because it is blue, although of course Uranus and Earth are blue as well (for different reasons). Neptune's blue is at least partly caused by the presence of methane in its atmosphere.
03-26-2007, 10:19 PM
why the orbit of pluto is different? why the rotation 
Linear Mode
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