How to make a theme?
 

Seems like a simple question, but not one that's been asked in recent time...

I've got a number of questions about how I should make my own theme for the site. I'll list them below:

1. How do you create a new theme? Just copy the "default" folder in the themes directory and start renaming / modifying?

2. I get that the theme uses theme.php for some kind of global php uses, and that theme.tpl defines a basic layout that is used by default for pages...

I am wondering how I handle page-to-page variation / multiple layouts withing a single theme. For example the home page will follow a distinct layout, yet internal pages will differ a bit with some being one column, others being 3-coloumn, others 2, etc...

Right now I have theme.tpl, do I just make more, like "home.tpl, 2_column.tpl, 1_column.tpl, 3_column.tpl"?