Around 2.4 AU.
The asteroid belt is located between Mars and Jupiter, It's a couple of million miles away.
No. Most asteroids in the solar system are in the asteroid belt, but not all. The ones that may threaten to strike earth, for example, are outside the asteroid belt.
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.