Two Questions Conserning QC.

1 How do I set Buoyancy of an object in the quake compile script (qc file)?

2 Is it Possible to set up the QC file to apply have certan gibs for certan areas like

windshield hit: windshield gib flies out and model looses windshield.
bumper hit: bumper gib flies out and model looses bumper.
hubcap hit: hubcap gib flies out and model looses hubcap.

Is that possible?