Both they can move as an asteroid field or as a lone asteroid, they also can be broken up from larger asteroid to make several smaller ones
Millions, if including very small bodies.
There are major 3 types of meteors. 1) Rocky meteor 2) Metallic meteor 3) a combination of both 1 and 3.
No. Asteroids are scattered throughout the solar system in various orbits, some of which are relatively stable. Some have orbits that pass near Earth. But the vast preponderance of large asteroids...
Yes, they even get delivered by little asteroid people in a first delivery space van.