Dynamic sub-navigation and other questions

Hi All,
I am building a site using WordPress as a CMS (it only has pages, no posts). It’s in development now at http://nugonutrition.com/wp/. I’ve got a few questions:

1) If you go to “nutrition info” or “about us” on the site, you’ll see a left-hand column that’s currently empty; this will be populated with sub-nav links which will change depending what area of the site you’re looking at. I know one way to do this would be to make several different page templates and hard-code the appropriate sub-nav items into the left column of each one; however, is there a way to do this dynamically, such that if I add a page to a section or change a page’s title, the sub-nav will automatically update to reflect this? Is there a specific plug-in that might do this?

2) How do I change the URL strings for pages, so that instead of, for instance, having “page_id=2” or something like that, I can use customized page name rather than an ID number?

3) What is the code to call a specific page to a particular place on your site’s Index template page? On my site’s homepage (Index template), I want to have 2-3 sections that can be updated automatically, but how do I get the template to call those pages to the right spots?

Thanks!
Nate