Labels of ready mix mastic at big box stores say not to use for glass tile.

True.

DH read that acrylic based should be used, is it true?

Acrylic, latex, or polymer modified, however it's worded on the bag. It's all same same. No matter how it reads, it should be a portland cement based powdered thinset.

Also same goes for grout, what type?

Same thing-- it should be a modified sanded grout.

Is it critical to use caulk at the base between the tile and granite or grout is OK?

Caulking ONLY.

Any advice for finishing the edges?

You can just finish with the factory edge of the glass, or you can use one of the metal finish bullnose strips available from Schluter. You could also trim it out in wood finished to match your cabinets, if you like. Lots of options. :-)

Thanks for the advice. I thought grout should be un-sanded? Would 3/16" v-trowel apply enough thinset?

Anytime I do mosaics, glass or otherwise, it's always sanded grout, and yes, a 3/16" v-notch should do you just fine.

Yeah...what that other guy said!

You wrote that it's "clear glass tile with a white backing". Is the white backing an epoxy coating? Or is the white backing a mesh that the tiles are glued to?

One thing to be careful of with glass is the thinset. If you leave ridges in the thinset, you might get uneven bedding of the tile and you;ll see the thinset ridges through the clear glass tile.

I'll apply the thinset (white thinset, not gray) to the walls using the notched edge of the trowel, that will get you a measured amount of thinset on the walls. Then I use the flat side of the trowel to knock the ridges down so the thinset is smooth. Then set your tile in that.

You want 100% coverage on the backs of the clear glass tiles.

Regarding white versus gray thinset, gray can muddy the color of the clear glass tile.

A slight tangent, but a lot of times with clear glass tile I've colored the white thinset with pigments for added effect.

Mongo

The glass in the photo above is clear, and the color is painted on the backs, as well. That's why the tile takes on a 3 dimensional appearance and you see shadows from the grout joints.

Thanks, the unsanded was recommended by the mfg to avoid scratching of the glass surface. Sounds like that shouldn't be an issue though. The backing is a white epoxy or some other coating so there shouldn't be any thinset showing through. But I'll take the advice about smoothing out, makes sense to get 100% coverage with the smaller tiles.