externals w/Rev v2

[Rod Price]

Hi,

I'm evaluating revolution v2 for use in building a nice GUI front-end
to some custom C code.  This C code implements a complex signal
processing algorithm, and we would like to build a GUI for demos.
So I have some questions:

(1) I've tried to find documentation on the Externals SDK without
     success.  I need to know what the interface to a Revolution
     stack looks like on the C end.

(2) Are there charting libraries (line graphs, etc) out there for Revo-
     lution?  Alternatively, can I use C-based charting packages within
     Revolution?  That is, can I write a C wrapper for a C charting 
library
     that will allow me to use the charting library as if it was a 
Revolution
     component?

Thanks,

-Rod Price