I love the Formula Rookie events, actually restarted them again last night.
Yes the cars can be a bit tricky, however keep in mind that they weight almost nothing, have no aero at all and on cold tyres that makes them a handful.
However they can be driven and driven quickly, the trick is to drive to the car not to try and tune them to suit a different style (as that will never work).
You have to get all of your braking done in a straight line, and once you turn into a corner you have to commit to it, try and adjust the throttle too much and you will most likely unbalance the car and spin. Only accelerate once you have apexed and are almost (if not completely) straight.
Once you get used to that you will find them quite straight forward to drive and can start to add in some gentle trail braking, but keep in mind its always going to be tricky in something like this.
I've driven a few older Formula Ford cars (on which these are based) and its one of the cars that PC recreates well in terms of how you have to drive the cars.
I would also recommend upping the number of laps, as you have found out 'hero' dives past half the pack don't end well in these (they don't like contact), so a longer race will give more time to pass a few at a time.
Nice crash however, remind me of mine in an FR, that was at Watkins Glen.
It is bloody annoying however that the AI has indestructible cars! My crash should have resulted in at least two or three of the AI cars being out as well.