I’m intensely curious about the screenplay template, though - usually software that does the formatting properly costs proper money.

If you're not markup-phobic, there's a screenplay class included with MacTeX 2007 (and probably other recent LaTeX distributions). Markup for a minimal screenplay might look like:

\documentclass{screenplay}[2006/11/15]

\title{The Title of Your Opus}
\author{Your Name}
\address{99 Any Street \\
Any Town \\ Postcode / Zip \\
Phone \\
email@whereami }

\begin{document}
\maketitle
\fadein
\intslug[day]{Johnny's House}

After a slugline you would typically have some description. This is simply
ordinary text with paragraph breaks as per usual.

\begin{dialogue}{Johnny}
After some description you would typically have some dialogue.
\end{dialogue}

\fadeout
\theend
\end{document}