If the angular momentum of a body is found to be zero about a point, is it necessary that it will also be zero about a different point?

If several forces act on a particle, the total torque on the particle may be obtained by first finding the resultant force and then taking torque of this resultant. Prove this. Is this result valid for the forces acting on different particles of a body in such a way that their lines of action intersect at a common point?

If the sum of all the forces acting on a body is zero, is it necessarily in equilibrium? If the sum of all the forces on a particle is zero1 is it necessarily in equilibrium?

If the resultant torque of all the forces acting on a body is zero about a point, is it necessary that it will be zero about any other point?

A body is in translational equilibrium under the action of coplanar forces. If the torque of these forces is zero about a point, is it necessary that it will also be zero about any other point?