we are making a backsplash for our kitchen counters with tile. We want to use glass tile insets from Lowes but they are expensive. What is the difference from regular glass? Coulld I get a sheet of glass and cut it with my wet saw ?

My husband's ex-student installed 700 ft of 16.5" ceramic tile in our kitchen, sitting room, back entrance foyer, and back bathroom. We bought the materials from Lowe's and he did the labor. It is obvious this kid wasn't experienced because my floors look aweful! The grout lines are too low and in some places the corners of the tile hurts my bare feet when walking on it. There are some air bubble holes here and there, and the grout looks uneven and crackly in some places. Also the grout turns dark and splotchy when it gets wet (it is supposed to be light tan grout). After reading some of the other threads today, I think this fellow mixed too much water into the grout and used a sponge that was too wet when wiping over the grout lines. My husband doesn't give a hoot about the floor and pretends that it looks fine. I hate how it looks and I want to redo it myself and I don't want the "installer" to come near my house to fix the problem because FYI: He wasn't licensed, he had worked with a licensed tile man for a few months, and was supposedly trained by the best installer in our area. My question is this: Do I have to completely remove the grout before adding new grout?