For Star Wars in Concert, you really don't have to worry about interacting because you are going to be swamped with photos. Basically you'll just stand there and pose while people wait in a huge mob to get a pic with you, at least that was my experience.
I usually stay more in character when talking with adults, but with kids I keep it really simple because they are timid and it's easy to scare them. I just high five them and then ask them if they like Star Wars. Sometimes I ask who their favorite character is, or ask if they want to hold my blaster.
I too went through a phase where I wanted to interact more and do fun things with people but was worried what they would think of me: Ryan. Then I slowly realized that they'll never know who is behind the mask and that freed me up to be bolder and try more things. The anonymity is actually a very freeing experience once you embrace it.