ubuntu studio install

[{ brad brace }]

when ubuntu studio is installed on a (system76 pangolin)
ubuntu system (8.10), does it replace the existing
applications?

does it make any sense to partion the drive as
ubuntu and ubuntu studio? does it make any sense to pay for
ubuntu installation and support only to blow it all off by
installing studio?

does a faster, smaller 7200rpm vs a larger, slower 5400rpm
drive make a significant difference for studio work?

thanks for any perspective

/:brad