Guess? How's this?
Beginner events = 4. FF, FR, 4WD and MR. Each with a PP limit, SRF allowed, Race tyres allowed.
Intermediate Events = 4. Same as above but Race tyres banned so only road tyres. SRF allowed.
Professional Events = 8. first 4 will by PP limited and drive train limited (FF, RF, 4WD & MR) to allow tuning to give the tuners their day in the sun. No driver aids
The other 4 races will also be drive train limited but this time will specify a specific car and no tuning allowed, so the driver is the difference. No Driver aids.
Tracks and PP level/specified car changes every two weeks.