How can I set footnote size to 10 and how to do basic line spacing?

Question

I am writing my thesis and it requires me to use font size 12(Times New Roman) for main body and font size 8-10 for footnote. The required line space is 1.5. And also the footnote should use basic line spacing. I am not sure whether I already had these or not. Can anyone help with this? Here are my Latex codes

\documentclass[12pt, a4paper, leqno]{article}
\usepackage{a4wide}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{appendix}
\usepackage{float, afterpage, rotating, graphicx}
\usepackage{epstopdf}
\usepackage{longtable, booktabs, tabularx}
\usepackage{fancyvrb, moreverb, relsize}
\usepackage{eurosym, calc}
\usepackage{amsmath, amssymb, amsfonts, amsthm, bm}
\usepackage{newtxtext,newtxmath}
\usepackage{caption}
\usepackage{mdwlist}
\usepackage{xfrac}
\usepackage{setspace}
\usepackage{xcolor}
\usepackage{subcaption}
\usepackage{minibox}
\usepackage{makecell}
\renewcommand{\theadfont}{\normalsize}
\usepackage{geometry}
\geometry{
 left=3cm,
 right=2cm,
 top=2cm,
 bottom=2cm,
}
\usepackage[unicode=true]{hyperref}
\hypersetup{
    colorlinks=true,
    linkcolor=black,
    anchorcolor=black,
    citecolor=black,
    filecolor=black,
    menucolor=black,
    runcolor=black,
    urlcolor=black
}
\widowpenalty=10000
\clubpenalty=10000
\setlength{\parskip}{2ex}
\setlength{\parindent}{0ex}
\setstretch{1.5}
\usepackage[backend=bibtex]{biblatex}
\addbibresource{refs.bib}

\begin{document}


Say hi to latex......\footnote{latex hello}


\end{document}

Answer 1

With a 12pt font as the main one then footnotes are set using a 10pt font, so you are OK.

You can get the current fontsize like this:

\documentclass...
\makatletter
\newcommand{\showfontsize}{{\f@size pt}}
\makeatother
\begin{document}
Some text\footnote{Footnote with a fontsize of \showfontsize}
\end{document}

Do you really want zero \parindent? When a paragraph break occurs at a page break how is the reader to know that the second page starts with a new paragraph?