Theme development

I might be missing it somewhere, but I can't find it in the forums.

The site I am building requires a couple of pages that have individual layouts. I want to be able to have full control of the HTML that is outputted in the Body section. In other words: The Header and Footer must stay as is, but the body needs to change according to my HTML only, and not all the "titles" etc. Here's an example:

My sheer, undying hatred of lists (ul/li) knows no bounds. I want to replace these aggravating annoyances with simple divs. How do I alter my theme to spit out divs instead of lis? Do I need to modify Drupal itself?

is there any detailed documentaion on this?

http://drupal.org/node/171213

I provided a screenshot which should be self-explanatory:
http://i138.photobucket.com/albums/q269/sayspo/snapshot4.jpg

The content needs to appear at the top next to the left sidebar, that is the main issue, and i really have no idea whats wrong comparing layouts.

The code for the style.css:
http://pastebin.com/f1c8563af

I wanted to know what code i had to insert here (see below) so that i could use my own search bar with drupals built in search functions. I need to use my own bar because of a weird theming issue.

Image of Search Bar:
http://i138.photobucket.com/albums/q269/sayspo/search.jpg

Code:

[code]
search

[/code]

I'm a designer, comfortable in XHTML and CSS. I've been building websites for a long...long time. I've got a few clients that want to move from hard coded designs to a database driven, CMS style format. In fact, I recommended this. Having gone through reviews for literally hundreds of competing CMS products I decided that Drupal may be the one for me. I should mention that my first choice was WordPress - I know, it's not a 'real' CMS - but more on that in a minute.

I am by no means here to start a flame war or to denigrate the hard work done by the Drupal community. Instead, I can hopefully cast some fresh light on who the user community is/will be, and perhaps make some suggestions as to how to make the product more useful to noobs like me.

My main goal with Drupal is to take an existing site, and Drupalize it - giving me the look I've already chosen, with all the backend functionality I need. So I Installed the software (installer was a breeze, nicely done!) and started reading about theming in the new 6.x themers handbook.