Configuring footnote position and spacing

I don't know if I got completely what you want to achieve...

• To "introduce some additional space in between one foot note and the next one, and between the first footnote and the line that separates it from the regular text" you can add the following line to your preamble (change 5mm to 1mm or whatever you need):

  \addtolength{\footnotesep}{5mm} % change to 1mm
  

• To "make the footnote number bold" you can add the following line to your preamble:

  \renewcommand{\thefootnote}{\textbf{\arabic{footnote}}}
  

• To "put it a couple points away from the left margin" you can load the package footmisc with the option flushmargin:

  \usepackage[flushmargin]{footmisc}
  

Complete code:

\documentclass[12pt]{article}
\usepackage[top = 1in, bottom = 1in, left = 1in, right = 1in]{geometry}
\usepackage{amsmath, booktabs, graphicx, setspace}
\usepackage[T1]{fontenc}

\usepackage[flushmargin]{footmisc}

\addtolength{\footnotesep}{5mm} % change to 1mm

\renewcommand{\thefootnote}{\textbf{\arabic{footnote}}}

\begin{document}
\begin{spacing}{1.9}
TEXT.\footnote{my first footnote is here.}

TEXT.\footnote{my second footnote is here.}
\end{spacing}
\end{document} 

Output:

\footnote{Hi}
\footnote{\vphantom{\Huge ${A^{A}}^{A}$}far away {\tt footnote}}

The result is:

Here is what I know to modify footnote settings. I think you could use this for some of your issues. Put the following in your preamble:

\makeatletter                                                                 
    \def\footnoterule{\kern-6\p@        % you can put other values to increase vertical space between rule and notes (just try out); difference between the values after "kern" is the width of the rule!
  \hrule \@width 2in \kern 5.7\p@}  % the in value is the length of the footnoterule
\makeatother

\addtolength{\skip\footins}{2pt}    % vertical space between rule and main text

\setlength{\footnotesep}{12pt}  % vertical space between footnotes

\let\origfootnote\footnote       % font size of footnotes; changes \footnotesize command only inside footnotes!
\renewcommand{\footnote}[1]{%
   \renewcommand\footnotesize\scriptsize     % here there is scriptsize in footnotes (example)       
   \origfootnote{#1}}