Sounds to me like you are looking for the enumerate environment. You can customize it with the enumitem package. You can break a line with \\ or start a new paragraph with an empty line or a \par.
Edit: You can customize the horizontal spacing with the keys leftmargin, itemindent, labelindent, labelwidth and labelsep, see page 4--5 of the enumitem package documentation.
\documentclass{article}
\usepackage[showframe]{geometry}% display page margins to make effect of leftmargin better visible
\usepackage{enumitem}% to customize enumerate/itemize/description
\setlist[enumerate,0]{% global customization of enumerate environment, see page 9 of enumitem package documentation.
label=\alph*.,
leftmargin=1cm,
}
% a custom command to save some typing, displays the value of a dimension in a table
\newcommand{\displaydimension}[1]{#1 & \the\csname #1\endcsname \\}
\begin{document}
\begin{enumerate}
\item you can \\
break a line
\item and you can \par
start a new paragraph
\item current values for horizontal spacing:
\begin{tabular}[t]{@{}ll@{}}
\displaydimension{leftmargin}
\displaydimension{itemindent}
\displaydimension{labelindent}
\displaydimension{labelwidth}
\displaydimension{labelsep}
\end{tabular}
\[ \texttt{leftmargin} + \texttt{itemindent} = \texttt{labelindent} + \texttt{labelwidth} + \texttt{labelsep} \]
\hfill\scriptsize (according to \texttt{enumitem} package documentation page~4)
\end{enumerate}
\end{document}

Please note that the values on the screenshot are not the default values, but for leftmargin=1cm, as visible in the source code. The default is leftmargin=25.00003pt.