[PyMOL] viewing electron density

Hi,

I am a new user of PyMol. I work with spherical virus structures and
some of my questions could be specific to these structures :

1) I am trying to get a cut away view of the density and the plane where
the cut is made is always shaded in black color. I would like it to be 
some shade of the
color I use for the surface in general. how do I achieve this?

2) Is there a command for masking density : for example, given a radius 
and center of the
density volume, can we carve out the density INSIDE this specified 
sphere or OUTSIDE the
specified sphere as the case may be?!

3) Is it possible to color the spherical virus particle density using a 
radial color ramp ?

Thank you for your help in advance!
-Padma

______________________________
Padmaja Natarajan, Ph.D
The Scripps Research Institute
La Jolla, California, USA.