Avoid extra space from vspace if section follows list (and questions related to enumitem)

Question

1. Why is that when I create a new length, and set it to \parskip, it becomes 0? (See earlier parts of MWE)
2. I would like my lists to appear right below text, and start a paragraph after. When doing this, if a section appears after the list, the spacing is too large; I believe because I used after=\vspace{...} in my itemize definition.
3. Is there a way to set sort of a soft-vertical-skip? Or maybe fuzzy is the right word. If anything but a section follows, use \parskip, if a section follows, respect the skip it wants?
4. I need to use before=\hfill to ensure that the list has proper spacing if it appears after a section, why? Aren't I using \hfill on a blank line? Perhaps this changes LaTeX to horizontal mode? Where the list would tell it to go into vertical mode otherwise?

\documentclass[parskip=full]{scrartcl}

\usepackage{printlen}

\newlength{\ParSkipAmount}
\setlength{\ParSkipAmount}{13.6pt plus 1.36 pt}  % determined by baseline skip
%\setlength{\ParSkipAmount}{\parskip}  % why does this go to 0 if I uncomment it??

\usepackage{enumitem} %
\setlist{nosep}  %
\setlist[itemize]{
    topsep=-\ParSkipAmount,% removes parskip, 
    before=\hfill,  % makes top of list appear in correct spot after section
    after=\\}% this cancels topsep

\newcommand{\examplelist}{%
    \begin{itemize}
        \item One
        \item Two
    \end{itemize}
}


\begin{document}

    \uselengthunit{pt}\printlength{\parskip},  parskip \newline
    \uselengthunit{pt}\printlength{\ParSkipAmount}, ParSkipAmount.  \newline
    Why is it that if I set ParSkipAmount equal to parskip, it becomes 0?


    \subsection{This section demonstrates the spacing I want}
        First paragraph.

        I like the list to appear right below text (via topsep)
        \examplelist
        And the next part to be a new paragraph (via after).
    \subsection{See how the spacing below this header and the following list is the same as the space for the previous section's header and ''First Paragraph''? It was smaller if I did not use before=hfill... why?}
        \examplelist
    \subsection{And also see how the space above this header is larger than that of the space before the previous section header? How do I get rid of the vspace on the after if there is a following section/subsection (by using setlist or patching)?}


\end{document}