There is no need to mask the tile. Masking could be handy if you want to do multiple colors and use the mask for no-go areas. I used multiple colors on the ones I did without any masking, which is impressive for me as my coloring ability is rated at: eats paste in corner. But as for lasering, not required.
In regards to settings, read the first several posts of the thread that kicked this craze off:
As you’ll quickly see, a wide range of settings works. Also, multiple methods of removing the excess color. I use off-brand magic erasers.