1. CSS Sculptor to design the site
2. DataAssist 2 to build the backend for the database
3. SecurityAssist to handle the login and to restrict access to admin pages
Would get you started. You can add fancy stuff later.
I would have tables for the users, groups, drivers and races. You would keep all the race info in the race table and pull cutoff dates from there to control when users could make changes.
You might want a master table to hold all the information pulled from the individual tables, so that users could change their anything in it that had their ID assigned to it. This would make it look like each user had their own page, but make it much easier to maintain. When they log in, they would be restricted to their own stuff.
Spend a lot of time in the database design stage to avoid surprises and costly rewrites.
Have a look at the Learning Resources too: