There's plenty of material on this site that should help you with your questions. I am about to write my very own templating module..
: the discussion that follows considers various templating systems in detail. Web Application Frameworks and their Templating Engines with a Comparative Study of Template and HTML::Template
compares several templating systems. Personally, I would go with Template
for an extensible and flexible system, but plenty of excellent alternatives exist (see also XSLT vs Templating?
and XSLT vs Templating, Part 2