You don't need an x brace on the door for an 8.50 cert. The basic 12 point cage is perfectly fine as long as it meets the 1 5/8 X .118 spec. It does need a dash bar though.
Best thing to do is get a current rule book as it is hard to describe what you need in text.
As far as licensing goes you will need a physical first, they will do a cockpit orientation test, where you are blindfolded and will have to shut the car down (pretend to shut down anyway) and exit the vehicle in a timely manner. Then 6 passes. When I did mine, they wanted me to make 2 mild, 2 moderate and 2 full, dumping the laundry on one of the full runs.
You can figure $500 by the time you are done, barring any items the car might need to bring t up to snuff.