eBusiness with Drupal

I'm looking for some sort of CMS system to support an eBusiness idea I have been pondering. I actually started cutting some code, and although the business logic is looking good, I need some form of automation with delivery.

The website will deliver information in the form of text, images and flash animations. This information will come from a MySQL database. The DB will also store information about users, what information they have seen, what they should see next, what options they might like to explore next, and so on. There is no "shopping cart," "forums" or community building in the plan. It's simply a system where people gain access with a username and password, then see the information presented to them. There's not even a requirement for a search option - the business logic and stored database information works out what a given user sees next.

Sorry to be a bit vague - I'm deliberately keeping my idea to myself for the moment. It's not pr0n! :o)

I started writing the business logic in PHP. I got the entry system working and the basic database planned out and functional. Then I started putting some pages together and realised I needed help. I need a mechanism that provides help with the following:

• basic webpages generated automagically from a template of some sort
• menus across the top and down the side that are created dynamically such that new options can appear as I think of them, or as the user wanders to a page where they might be relevant
• the ability to accept, with little effort on my part, my exisiting (and to be developed) business logic code
• the ability to hand over things like login authentication to me - my idea requires several "grades" of user, who will get to see different areas of the site. I suspect an off-the-shelf username/password mechanism won't be good enough
• the ability to deal with information from cookies
• features that help deliver my content - a webpage from a template that has some text and a flash animation from a database, for example

I'm not scared of learning or coding this myself. To date I've been working on the basis that I'm going to write the whole lot myself from scratch.

I initially started looking at CMS systems when I came across the requirement for webpage menus. From there I started thinking about page templates and other such mundane things, and decided there ought to be a better solution than writing it all myself. I investigated Midgard but it seemed ridiculously complicated to set up.

The question, then, is should I be investigating Drupal? As a CMS, it looks like it would do what I want, but it does seem to lean towards the community development/portal kind of website, as opposed to an eBusiness idea.