Advice on cabinet construction and counter height.

I am a homeowner and about to start building my
kitchen cabinets.  I would like to have granite
countertops installed, and I have a couple of
questions regarding what a granite installer likes to
see when he comes out to measure for the job.  First,
I intend to use adjustable leg levelers instead of a
platform for the cabinet boxes.  Will the legs support
the wieght of the granite tops?  Second, I installed a
bay window in my kitchen a few years ago, and the
plywood base for the window is 35.75" above the
installed floor level.  I know the standard countertop
height is 36", so I'm wondering if the granite that I
want to extend into the bay window could be milled
thinner so as to allow a standard counter top height?
Third, I would like to know if 5/8" plywood would be
OK to use as a support for the granite.  In my
thinking, this would allow 1/8" of the granite
countertop edge to extend beyond the top of the
cabinet faceframe, thus hiding the plywood better.

Thanks in advance for any response.

Jerry
Valencia, CA