My 1999 jdm sti trans (V5/6 were the same, as long as it wasn't a RA) came with a starter, clutch/flywheel, and slave cylinder. I ended up using a 02 wrx ACT Light weight flywheel, oem grade excedy 02 wrx clutch kit. a stock 2.5rs manual pedal set will work. you'll just need a good working slave cylinder and hoses/tubes to connect the rs master cylinder to the slave. I personally have a 02 wrx pedal set in my car, because i like the aluminum pedals, still bolted right in, and came with a master cylinder/brake cylinder.
All subaru turbo 5 speeds use the same clutch/flywheel/slave cylinder from 1991 to 2004. Legacy SS, all jdm turbo cars, and the first years of USDM wrx's.
(in 05 the forester xt and Legacy gt's got a push type slave. WRX's didnt switch to the push type untill 2006).
IMO, when doing research and collecting parts, treat the trans like a 2002 wrx trans. the internals and FD are different, but everything else will be the same to get it in your car. even the linkage, axles, driveshaft... are all the same as 02.