Barb,

I've been in the tile industry for 25yrs. The most important thing to remember with glass is the mortar you use! It should be white thinset for your glass mosaic. The Mapei company has the best in the industry!! It is specified for white glass, & stone!
I honestly would not worry about the grout! Staining rarely occurs on a backsplash! I know they have grout with a little sparkle to it and I believe the company Laticrete carries the product!
One last point, mosaic work is very difficult to do! It's not just placing sheets on the wall. It takes someone very experienced to layout & do the proper cuts! I've seen some spectacular installs and a lot of botch jobs!
My advice if you decide to hire a professional ask him what his experience is in mosaic work and job specific glass work!
Good luck with your project!