Don't get the gel if rain is forecasted for the day. We got it done and shortly afterwards it started to rain, the gel was everywhere and ruined DS9 shirt. I ended up having a reaction to the gel and broke out in a rash. We had to leave the park to go wash it out. It is very cute as long as it has time to "set" a little and will hopefully stay were it is supposed to.
Yes they can do other colors, I've seen blue, red, and green.