Is it an import? If so, it'll probably have a torsen LSD which is great for starting out. If it's a UK car then chances are it'll have an open diff which might not be ideal. I've not tried skidding one of these on an open diff. If you struggle then maybe seeing about getting a LSD or welding your open diff might be an idea, but try it out first and see how you get on.
Otherwise some half decent shocks, and maybe a bucket seat and you'll be well away.
It just so happens I have some Tein shocks and a Cobra bucket seat for sale in the parts section
I'll be at DWYB next month in my car, which is very similar to yours. Come and say hi!
4 spares is probably enough, and you can buy extra tyres at DWYB if you run out. The hardest thing is fitting them in the car.