In Effex each particle can carry properties of different data types: Scalar (floating point), vector (three scalars) and state (boolean).

There are predefined unique properties. Unique because each particle can only carry one unique property at a time.
For example a particle can only carry one color property. It doesn't matter if you create more color properties. As it is a unique property it will only be available once per particle.

So you would only create more color properties in your Effex Scene if you for example need to assign different initial colors to different particles.
If you are reading out the color property somewhere (in a shader or similar) you only need one property node though (and it doesn't matter if it was the one you assigned the property with in the first place).

Then there are non-unique properties which are custom properties. A particle can carry unlimited amounts of this property kind and the interfaces (so the objects in the C4D object manager) are directly linked to these properties. Reading out these properties require the exact interface to be used to read the property (the object in the object manager is like the id of the property).

Attaching properties to particles is done directly in the Particle Emitters.

Two properties are always available per particle and do not need to be attached: Position and Velocity.

This is a list of the available predefined unique properties (that can be created from within the Effex menu or via corresponding Candidate buttons):

Scalar Properties:

Age - the life time of a particle. Once assigned in an emitter the particles can die.
Radius - the radius of the particle
Density - the particle density of the particle. This can be filled automatically by a volume properties node.
Viscosity - the viscosity of a particle
Pressure - the pressure of a particle
Temperature - the temperature
Fire - the fire value of a particle
Fuel - the fuel value of a particle


Vector Properties

Color - the color of a particle
Old Position- the old position of a particle
Velocity - the velocity of a particle
Vorticity - the vorticity of a particle. Automatically available for Vorticity particles
External Forces - the external force of a particle. Automatically available for Diffuse particles.