Please help a newbie out... What contributions are needed for me to do this?

Hello, I currently have version 6.1 but am having it downgraded since I see that there aren't much modules for it yet. Here is what we're trying to do an any assistance you all could lend would be greatly appreciated. Also, I'm a former Joomla! user and I'm so excited to enter into the world of Drupal!

Okay, let's get down to business:

We currently use a highly modified version of osC for our shopping cart. We have a wholesale website in which our users have to be approved before seeing prices and being able to make purchases. We would like to have the Drupal and osC share user information so that when the user is approved through osC they will also be added as a user to Drupal.

The Drupal will have certain areas visible to the public and other areas that will be member's only.

There will be a blog that is available only to the user.

We also use SugarCRM and it is currently integrated with our osC. We would like all three to be integrated. Now, you experts, how would we go about doing this?

Thank you!