i have heard that to change the clutch on 2000 classic shape the engine needs to be taken out and i have also heard you can put the car on 4 post ramp and do it from the transmission end. what is the best way and how long should this take? thanks

 

no, the gearbox is removed, leave the engine in.

I sugest you use a subaru specialist if one is near enough, otherwise find an experienced garage, there are a few foibles to the Impreza such as having to remove the pivot pin the clutch fork is mounted to, otherwise you cant get the box off.