QTR-Quadtone RIP

Does anyone have a recommendation for which curve of the set that comes with QTR for 
the Macintosh would work best with Epson premium luster paper using standard Epson Inks 
on an Epson 2200 printer?  Premium luster is not one of the choices offered in the 
provided set.

Second, of the options for printer profiles, any suggestions for the same parameters above?  
What is the difference between QTR-RGB and QTR-Gray choices?

Thanks for any help here.

Mike