Yes. Many funnel clouds never touch down.
They are called funnel clouds or, more often, twisters.
Cumulus clouds don't so much appear in tornadoes. It is more accurate to say that tornadoes descend from cumulonimbus clouds.
Yes. The first known tornado was recorded in Ireland in 1054.
Funnel clouds are the result of rotation in thunderstorms, induced by wind shear, becoming tighter and more intense, stretching toward the ground. If the rotation reaches the ground it is considered a tornado. See the relate question for a more detailed explanation on the formation of tornadoes and the storms that cause them. The visible funnel itself is a consequence of the pressure drop inside the vortex. Air enterin the vortex experiences a rapid drop in pressure which in turn causes a drop in temperature. This temperature drop causes the moisture in the air to condense into tiny droplets, forming a cloud.
The funnel clouds themselves, are not that big, usually no more than 200 yards wide. The weather front that carries them may be vast. Some tornadoes may grow to overa mile wide and a handful have exceeded 2 miles. These might be considered vast by human standards, but are still small by weather standards.
Sometimes. Tornadoes often lift at least some soil into the air, and so create a dust cloud of that color. However, the actual funnel of a tornado is condensation and will more closely match the color of the clouds overhead.
Not really. Although tornadoes form most easily from clouds with low bases, the height of cloud based doesn't tell you much. Other signs, such as rotation in the clouds, are far more telling.
No. Texas gets more tornadoes than any other state.
The funnel of a tornado is the result of moisture inside a tornado condensing. As the air rises it cools, allowing more moisture to condense, therefore the funnel gets wider the higher up you go.
Tornadoes can happen in the tropics but they are more common in temperate latitudes.
Tornado Alley
yes