As for the (a) the total force of the ground/hinge (e.g. thrust or normal force + friction) is generally neither vertical nor horizontal. EDIT: You can obtain the force of the ground/hinge by calculating the force of the rope first, and then add all three forces together to get zero.
As for the (b) you have three forces acting to beam, force of the ground, gravitational force and force of the rope. Since problem suggests "considering equilibrium", torques of these three forces must equal zero.
(2) Force at point B is simply the force of rod BD to rod AC (and vice versa). Effectively, you have three forces acting on rod AC. Note also that the force of the rod BD is along its direction (because it is limited by two joints at its ends and there is no force in between).