^^ get either the koni sport suspension kit (1.5 inch drop with adjustable dampers)
or h&r race springs with shortened konis (2 inch drop, you can get it from fs werks if you call them) as for swaybars find a 22mm front and a 25mm rear swaybar from eibach or intrax. (summit has the intrax bars) you'll find the coilovers arent really necessary for autocross unless your a super hardcore knid of guy, damping adjsut ment alone will make the car handle vastly different. then look at some lightweight wheels and sticky rubber.
however if your first etting started i suggest going in totally stock, and learnin the limits of the stock focus before putting any mods on. also dont worry too much about power. work on getting off the line quick and staying quick through the corners
your car will never be like my car, after all you have common sense......