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?

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 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?

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?

A rectangular brick is kept on a table with a part of its length projecting out. It remains at rest if the length projected is slightly less than half the total length but it falls down if the length projected is slightly more than half the total length. Give reason.