Ended up using 3/16 v-notch trowel. As recommended by the guy at lowes. That said, he said I might want to go up to 1/4 if I was using the "custom" mortar (which I think is more like mastic?) vs the premium mortar.
I did use a wetsaw like this:
the stone cut very easily as long as I went slow. The nice thing about the simple tabletop wetsaw is that it made it very easy to cut and grind individual pieces. That said, it did make a mess so I was happy that the weather allowed me to use it in the garage.
After sawing I sprayed each piece clean and let it dry for a bit while I was putting up the mortar. One of those pump cans that you pump some pressure into ahead of time would have worked, but since I couldn't find mine, I ended up filling my wagner power painter with water and used that. Either way I'm glad I did that - I think it was more effective/less messy that cleaning them once they were on the wall.
I found some straight 1x2s that worked great for holding up the floating areas. It is debatable whether I needed them to avoid sag - but they were great to make sure things were level.
I also got a rubber mallet and a scrap piece of the 1x2 for taping the sheets together to make the seams disappear
I also had an old padded drywall sander that I used to push on the tiles into the mortar for more even pressure.
Other tips are make sure you take a quick look at the seams before you move on to the next sheet. slightly moving a couple of stones can make all the difference in avoiding a zipper look.