[TYPO3] Multiple Templates on One Site

[Lee M. Childress]

Greetings:
I'm slowly getting the hang of Typo3 and liking it more and more. I have spent some time reading tutorials and google-ing, but haven't found a good answer to my question.
 
My site tree looks like this:
 
HOME PAGE    |    --- TOPIC ONE    |       |    |       |__ SUB TOPIC1    |       |    |       |__ SUB TOPIC2    |    --- TOPIC TWO... 
 
My home page will have three columns, my Topic pages will have two columns, and some of my sub-topic pages will only have one column. Otherwise, the template will be the same throughout (except that the main navigation I want to show only topics on the Home page, and then sub-topics on the topic pages, and sub-sub topics on the sub-pages ... 
 
What is the best method for developing and recycling several different templates in Typo3 for the same site? Can someone point me to a really good tutorial or show me an example? I learn best from seeing something in print.
 
Thanks in advance for your assistance.