\usepackage{} -- threeparttable, Add Footnotes to Tables, Separate From Document Footnotes

\usepackage[para,online,flushleft]{threeparttable} % Custom captions under/above floats in tables or figures.

%  The threeparttable Package Documentation (PDF).
    
% [para] --Notes come one-after-another without line breaks.
% [flushleft] -- No hanging indentation on notes.
% [online] -- \item tag is printed normal size, not superscript.
...

\begin{table}[]   
\small    % Changes overall font size of the table
    \caption{Table caption.}     % \label must immediately follow \caption % \captionof doesn't work here.    \label{tab:table_label}           \centering    % Centering works and is preferred.  PDF shows the use of \begin{center}    \begin{threeparttable}    % Changes overall font size of the table
    \begin{tabular}{lccccccc}
    \toprule    \multicolumn{6}{c}{Table Name} \\ % 6-column table.        \midrule          & \multicolumn{2}{c}{Column Group 1 Name} & \multicolumn{2}{c}{Column Group 2 Name} & \\ % Blank before the first & allows for a 'blank' column name.  Same with the blank after the last &.  Two multi-columns.
        \cmidrule(r){2-3}    % This gives a mid-rule for the grouped multi-column.
        \cmidrule(r){4-5}
          & Column Name 1a & Column Name 1b  & Column Name 2a & Column Name 2b & Column Name 3 \\
        \cmidrule(r){2-3}
        \cmidrule(r){4-5}
        \cmidrule(r){6-6}    % This gives a mid-rule for the last single column.
        Row Name A\tnote{$\dag$} & Value A1a & Value A1b & & Value A2a & Value A2b & & Value A3 \\    % \tnote{1}, \tnote(a) also work.
        Row Name B\tnote{$\ddag$} & Value B1a & Value B1b & & Value B2a & Value B2b & & Value B3 \\
    \bottomrule    \end{tabular}
    \begin{tablenotes}
        \item[$\dag$]{\footnotesize{Footnote Text for $\dag$.}} \item[$\ddag$]{\footnotesize{Footnote Text for $\ddag$.  {\color{Crimson}This still works.}}}   

    \end{tablenotes}
    \end{threeparttable}
\end{table}

...

This is the only option that didn't interfere with the document footnotes or numbering.  Footnotes appear at the bottom of the table much like an un-numbered second caption might.

\usepackage{} -- textcomp & \celsius vs. {\textcelsius}

So far the only way I've found to properly insert ˚C is to

\usepackage{textcomp}

...

{\textcelsius} % Note this won't work in math mode.  No different spacing is needed around this.

_____________

{\celsius} % Does not work.
\celsius % Does not work, even in math mode.
\textcelsius % Does not work.

I had previously found an online forum that suggested using $^{\circ}$C every time, but that's tedious, ONLY works in math mode, and had caused some errors.

Spaces Following Abbreviations, and A Cautionary Tale

# 7 on Reed College's Ten Strange Things You Need to Know about LaTeX says:

• LaTeX will always force a slightly larger space after a period, but with abbreviations like etc., an extra space is incorrect. Place a \ character directly before a period that should not have any space, and put \thinspace directly after. For periods after single letters ( E. coli), LaTeX does not use an extra-large space. Thus, to get et al. and etc., write: et al.\thinspace and etc\.,

Do your own testing.  Limits of typesetting on blogger.com mean I cannot show exactly what my TeXshop version produces, and I suspect it has more specific programming included than is believed by that guide. 



\emph{E. coli} et al. etc.,

     % E. coli et al. etc.,  
     % This line looks best overall.


\emph{E\. coli} et a\l. etc\.,

     % Eċoli et alėtc; 
     % This line has has a "dot-c", a "dot-e", is missing two spaces, and has a squished semi-colon.

\emph{E.\thinspace coli} et al.\thinspace etc.\thinspace,  
     % E. coli et al. etc. ,   
     % E. coli looks best here.  Not enough space after et al.  Obvious space after etc. ,

I think I'll stick with regular spaces unless otherwise indicated by the thesis editing officers.

\cite{} for Citations

{~\cite[Fig.~7b]{Lname2000}}  ~ is a non-breaking space.  [Fig.~7b] is an [option] to include a specific element or page number from the reference. 

\emph{emphasized text} vs. \textit{italicized text}

\emph{emphasized text} vs. \textit{italicized text} -- If your captions are already italicized, \textit won't show any effect.  \emph can be nested such that an emphasized phrase within an italicized phrase will look like this. 
_NEED REF_