Based on our best available theories including the Standard Model, the answers would be:
Ans 1. Forces between particles arise from the exchange of force carrier particles which are bundles or quanta of energy of a particular kind of field.
Ans 2. Higgs boson, the force carrier of the Higgs field gives mass to fundamental particles.
Ans 3. The Standard Model contains the particles, each of which is an excitation of a particular force field. The electromagnetic force can be described by the exchange of photons. The nuclear force binding protons and neutrons can be described by an effective field of which mesons are the excitations. The strong interaction between quarks can be described by the exchange of virtual gluons. Beta decay is an example of an interaction due to the exchange of a W boson, but not an example of a force. Gravity is not a part of the Standard Model, but it is thought that there may be particles called gravitons which are the excitations of gravitational waves.
Ans 4. If all the forces in the universe were eliminated completely, I think we would have any matter, let alone the idea of matter standing still. There would be nothing to hold up elementary particles to form matter.
Ans 5. By movement of force carriers of the respective force field which transfers momentum from one particle to the other.