Yes you can change the pedal yourself, it should take you about two hrs and is actually better that you do it because it takes some adjusting it to your preferred pedal feel,engaging point afterward.

As far as replacing your clutch goes it may be a good idea as well if it is the csc .If it's bad that means it might of leaked oil in your clutch ,pressureplate and flywheel. I personally would not go back with the oem csc due to it will fail again and have to drop the transmission again.(due to the fact that it gets hot in thier and the piece is made of plastic)Move the slave cylinder outside so if it does fail it will be easily accessible.Cmak is a very easy install