Is a soaring arrow a projectile?

yes

A projectile is any object projected into space (empty or not) by the exertion of a force. Although a thrown baseball is technically a projectile too, the term more often refers to a weapon.

because that is how you spell it

Velocity.

A projectiles motion will change little because of its weight, weight, depending on propulsion will mainly affect trajectory and distance. Expotential forces(gravity, wind) tend to affect projectile...