How many Types of Force are there in a classical mechanical system?

Real Forces (Forces that must be considered first)
1) Pressure
2) Tension
3) Gravitational Force
4) Frictional Force (Results from pressure that causes surface molecules to collide)

Imaginary Forces (Exists only because real forces exist)
1) Derived Forces (Gravitational Force must be seperated into 2 directions at a frictionless slope, and itself perished)
2) Centripetal Force

Opposing Force (Must act on different objects and must be opposite in direction)
1) Pressure - Pressure
2) Tension - Tension
3) Gravity - Attract - Attract
4) Friction - Rub - Rub

Will an astronaut feel an opposing force if
he stands on the ground and pushes an orange?
he floats in space and pushes an orange?
he floats in space and pushes the moon?
He wont feel an opposing force when he is at space, but he will accelerate at the opposite direction of the force he apply, which maybe will make him think that he successfully pushes the moon.

External Force and Internal Force
1) External Force is the force that is not paired up within the system, and will eventually cause the system to accelerate or if the external forces sum to 0, the system stays still.
2) Internal Force will never cause any changes to the "SYSTEM", in terms of displacement, velocity, acceleration, or energy.
3) If something does not move or is in an equilibrium, the external force must always be 0. (Applies even to water)[Pressure and Gravity is the 2 forces that shapes all liquids]