The best way to start this project?

Edited: Sorry, this was not a support question
Hi, could someone please help us to see if this is possible using WPMU?

We are setting up a portal, and i wonder if anyone could give us a tip on what would be the best way to set it up.

The Idea:
A start page portal based on a directory where the people who set the site as their start page, earns points every time they open their browser (1 view = 1 point). You sign up and get your affiliate URL. You use that unique URL as your startpage (that way all the "hits" will be counted). When you log in, you are loged in on every sub domain aswell.

Key features:
Membership (Same login and pass for all features)
Affiliate (every member has their own URL)
Directory
Classifieds
Jobs

What i'm thinking:
domain.com (directory plugin)
jobs.domain.com (Jobbroller from appthemes)
classifieds.domain.com (classifieds plugin)

Is it possible to do this, and is there a better way to do it?

Thank you.