Typically, if you are re-using your flywheel, you should have it re-surfaced so your new clutch seats correctly. If you're unable to have it resurfaced (it needs to be replaced) you should replace it at the time of doing your clutch. Not sure about the movement on your R57. However, go to our R56 clutch replacement article here:
Mini R56 Clutch Replacement | R56 Cooper (2007-2013) | Pelican Parts DIY Maintenance Article. At the bottom is a comment box. Copy and paste your question there and Nick should get back to you with additional input.