Why do the planets rotate and orbit the sun?

This sounds like a stupid question, but it's very important to the understanding of how the planets came about in the first place, and keep in mind that what I'm about to say is only a theory. No one was around when it happened.
The nebular hypothesis is currently the best theory for how planets form, but there are many other theories.
One of the criticisms of this nebular theory is how does dust only one millimeter in size stick together. This problem was solved by studies that showed that electrostatic force is able to cause dust to clump together. Astronauts on the International Space Station proved this by showing that dust in a clear plastic bag clumps together while in zero gravity.
The other problem is how the cores of the gas giants formed so quickly during the ten million years or so that it took for the accretion disc around the proto star that was to become our sun to form planets. This would make a good thesis subject for a budding cosmologist.
Our solar system is the result of a supernova. A huge blue star exploded about five billion years ago and in the process sent a giant cloud of gas, dust and debris several light years across out into the nearby space of the Milky Way galaxy. A star coalesced out of this cloud of mostly hydrogen gas to form our sun and the rest of the gas, dust and debris began to circle around it as it compressed down well enough to cause the fusion of hydrogen to helium. This ignition explosive event forced the gas and dust cloud circling around this proto-sun to move away and then begin to form planets by a process called accretion. This process began around 4.6 billion years ago.
But why did the star that formed spin and the planets that coalesced out of the dust orbit the star? That's because of the conservation of angular momentum. As a nebular cloud of gas and dust condenses, its mass grows and this causes rotational velocity to increase. The initial rotation was started by the impact of another supernova, which compressed the gas more and set it in a rotational motion, or so the theory goes. Think of a spinning skater. When the skater pulls his or her arms closer to their body it causes their effective mass to increase and the spinning velocity increases. This has to do with angular vector inertia increasing. It just works that way.
Since the sun's rotation and the orbits of the planets are in the same direction, this is one proof of this angular momentum physics concept.
Visualize, if you may, a giant cloud of gas and dust a 1000 AU across (AU - astronomical unit is the distance from the Earth to the Sun) spiraling into a spherical ball of compressed hydrogen gas at the center that continues to grow in size and mass, eventually glowing hot because when gas is compressed it heats up. This process speeds up until the center proto-star begins to fuse hydrogen into helium, which sparks an explosive blast of energy out to a disc of gas and dust that is orbiting the proto-star, now a new star in the universe, shining brightly and proud. Over a few million years, the gas in this accretion disc begins to form giant gas planets and the dust coalesces and begins the formation of rocky asteroids that collide to form planetoids, all while orbiting the new baby star.
Collisions of asteroid-size rocks imparted spinning momentum to the new planetoids, and these collisions continued throughout the planet's formation period. Rotation is also the result of dust spinning around as it coalesces, and the combination of this natural spinning effect and collisions is why our planet Earth rotates, although it once rotated much faster than now. When a Mar's size planet collided with it in a glancing blow to form the moon it added a rotation to the Earth. This new moon was much closer, appearing in the sky as giant orb. Over time, gravitational tidal forces slowed the Earth's rotation and pushed the moon away to where it is now. This process is still occurring and eventually the moon will be free of the Earth's gravitational influence, but it won't happen for a long time.
Visualize what it must have been like during the last great bombardment period when rocks were banging into planetoids, blasting hot magna out into space and causing all sort of destruction and buildup of massive planets. There were hundreds of proto-planets in those days, but only the strong survived, and fortunately for us, the planet Earth was one of those survivors.

Thanks for reading.