Things to buy after you get the car:

-Fix any and all maintenance items
-Snell SA2000-rated helmet
-Falken Azenis 205/50-15 tires
-Membership to yer local autocross club

Don't worry about setting up the car until you get used to tossing it around. Besides, if you learn to drive well with the stock setup then you'll have a much faster learning curve after upgrading.