Questions about Darcy's model in Comsol gallery

I have some questions regarding Darcy-Brinkman example, Which I have found online in Comsol gallery. I will be more than happy if you can help me to figure out my problems or tell me how can I find my answers. The questions below are about the model provided for this example.

1) Why are the variables defined in the model and what is their application? (what are they used for)
2) When I expand the Darcy's law part, I can see Fluid and Matrix Properties 1 and Storage Model 1. I don't know what is exactly done in these two parts and what are the differences?
3) Inward Mass Flux in Mass Flux 1 part in Darcy's Law is considered 0.5*W*dl.rho/(pi*r*b), what is dl.rho and why it is written there? Because it should be equal to W/(2*pi*r*b) based on what is described in related pdf.
4) In Initial values 1 in Brinkman Equations part, the ubr=eps in z direction. What is this?
5) On page 7 in the pdf, two plots are provided. Where can I find them in the model? (how can we use the model to make the plots with desirable parameters in x and y axis?

I attached the related pdf file and the model for you to make it easier to find them.

Thank you very much for your help