cleaning marble?

It just installed Marble (http://www.lightemprador.com) (so nothing has gone wrong yet :-) )  I am
wondering what products I can use to maintain it and (http://maplered.com) clean it.
It is a combination of Durango honed and (http://maplered.com) Calcutta Gold Marble (http://www.lightemprador.com) .  There is
as glass door surround.  The installer sealed the Stone (http://g603.net) ....then
grouted.  Should the grout be sealed to keep it from mildew?
If I get mildew, soap scum or hard water stains at some future
date...what can I used to remove them without hurting the tile?  I
understand (http://maplered.com) not to use anything acidic.
It's a beautiful shower...but with all the cautions...I'm now afraid to
even use it!

Thanks,
Toni Lockhart.