Best way to index in spanish / xindy on windows? / makeidx and spanish accents

Question

I am unluckily on a Windows machine and that seems currently tough to be changed. I want capital letters to appear before each block in the index. This is my current .ist file:

headings_flag 1
heading_prefix "\\textbf\{"
heading_suffix "\}"

By running this in the preamble:

\usepackage{imakeidx}
\makeindex

I get the following output:

Things I don't like: I would prefer the word "Símbolos" rather than "Symbols". I also would prefer words like "álgebra" to be in the A group (to this I might just resign to do something like \index{algebra@álgebra} but hopefully there is going to be a better way. I have seen the post here Sorting index entries with accented words for the case of portuguese. It uses xindy but I am not sure if it works on a Windows machine because I have tried for a long time to do what is stated in the post and I don't seem to get their results. When I type xindy directly on the command line I get an error saying that xindy is not a valid command.

I would appreciate if someone can give a user-friendly explanation of how I can achieve to to this. Here is the essential part of the code I am using:

\documentclass{book}
\usepackage[T1]{fontenc}
\usepackage[latin1]{inputenc} 
\usepackage[spanish,mexico]{babel}
\usepackage{subfiles}
\usepackage{appendix}
\usepackage{makeidx}
\makeindex
% ----------     BibLaTex     ------------ %
\usepackage[style=american]{csquotes}
\usepackage[backend=bibtex, citestyle=numeric,bibstyle=authoryear,url=true,firstinits=true]{biblatex}
\usepackage{tocloft}
\renewcommand{\cftchapdotsep}{\cftdotsep}
\usepackage[nottoc,numbib]{tocbibind}
\DefineBibliographyStrings{spanish}{%
  bibliography = {Referencias},
}
% ----------      Hyperref    ------------ %
\usepackage{hyperref}
\hypersetup{%
    colorlinks=true, 
    citecolor=blue,
    linkcolor=black,
    urlcolor=black} 
\addbibresource{ref.bib}
% ---------    Cuerpo del documento  -------------- %
\begin{document}
\maketitle
\frontmatter
\tableofcontents
\mainmatter
\appendix
\backmatter
% ------     Referencias  ---------- %
\printbibliography[heading=bibintoc]
% ------     Índice  ---------- %
\phantomsection
\printindex
\end{document}

Answer 1

Add to your .ist file the line

symhead_positive "Símbolos"

to change The Name "Symbols" in your index to that you want.

With MakeIndex you will need to use

\index{algebra@álgebra}

for a better sorting.

How to install Xindy with MiKTeX please have a look to question How to use Xindy with MiKTeX.