2
No, Smarty templates are not like BBCode. BBCode is an interface the user can use to safely markup submitted content.
Smarty is a templating engine that operates on the system level, and provides the system with a way to access dynamically generated output.
They both operate on a different level.
But, this answers your topic question, but probably doesn't get you much closer to what you're trying to achieve.
XOOPS has BBCode too, and it's all in the text sanitiser scripts. I'm no coder, so I can't help you there, but that's where to look.
Herko