Having riden in an Ohlins-clad STi, I can say that I would not pay that much money for them.
You are much better off saving the money, using the stock struts and seeing how far they take you on the track, then getting coilovers, IMO.
The Ohlins are worth $1200-$1400, IMO. They are not priced for what you get performance-wise and I don't like that I've already seen a pair completely corroded after one winter in Ohio.
Now, what you can do in the meantime, is wait for the Prodrive/Bilstein RB320 kit to come out. They will be coming with Bilstein struts with the PSS-9 internals. I bet that those struts will give you 99.5% of the performance as the Ohlins will for a bit less cash. Adjustability isn't that important with a strut and spring setup.
For your trackday, definitely get the pads and fluid. The stock stuff won't hold up to repeated pounding.
The rest isn't really necessary, like Troll said, the driver mod will give you the biggest gain out there, although I'm not sure a base civic could deal with a modded STi in the hands of anyone but helen keller :p