Modify output of contour polar plot from input data

Question

I have used @BambOo's answer to this question to generate a contour polar plot in tikz. I have updated the data file. The example code works for my data and generates the following output:

I have the following questions:

1. The colour scale in the legend is different to the colour scale used in the! How can this be corrected?
2. How can I add the information on the r values, similar to Python plots?
3. Why is there a white spacing along the circumference of the plot?

MWE

\documentclass[tikz]{standalone} 
\usepackage{mathtools} 
\usepackage{pgfplots}
\usepgfplotslibrary{external} 
\usepgfplotslibrary{colorbrewer} 
\usepgfplotslibrary{polar} 
\pgfplotsset{compat=1.16,cycle list/Dark2}

\begin{document} \begin{tikzpicture}
\begin{polaraxis}[
        width=4in,
        height=4in,
        tickwidth=0,
        xtick distance = 45,
        separate axis lines,
        y axis line style= { draw opacity=0 },
        yticklabels = {},
        ymin=0,% ymax=1,
        colorbar,
        colorbar style={
                tickwidth=0,
                ylabel={$\omega$},
            },
        colormap name={viridis},
        axis on top=true,
    ]
    \addplot3 [contour filled={number=55}] table[x expr=180*(\thisrow{theta})/pi,y expr=\thisrow{r},z={CFIr}] {CFIr.dat};
\end{polaraxis} \end{tikzpicture}

\end{document}