Question: Does anyone know what Mr. Boy's power is?
Answer: He doesn't have one. Like Will in the beginning, he was assigned as a sidekick because he didn't have a power.
Question: How did Lash find the Secret Sanctum?
Answer: Will took Gwen to the Secret Sanctum. Later it's revealed that Gwen is really Royal Pain and since she saw the location of the Secret Sanctum, she would have told Speed, not Lash, as his super speed would be able to get him in and out without setting off the alarm. If Lash had tried to get into the Sanctum, he would have been caught.
He entered while Gwen was still visiting for the first time before she left.
Question: Will and his father slide down poles to get to the secret sanctum. How do they get back out?
Answer: Elevator, stairs, secret entrance used when the leave, like the batcave, or he used his super strength to leap both of them out.
Question: What song is playing when Will dumps Gwen?
Answer: Voices carry.
Question: Why didn't Royal Pain use the pacifier on Will when he comes to confront her at the end of the movie?
Answer: She is holding Will's father, The Commander, in her arms. She didn't have the Pacifier, besides he was a high school student superhero, with no real combat experience. She thought he would be a pushover in battle.
But she had the Pacifier before. She could have gave Will's father to Lash (The evil guy who works with her) and got the Pacifier and shoot at Will. Why fight with Will if she can turn him into a baby like the others?
Answer: I'm pretty sure he has super jumping as you can see when there was an explosion in the science lab and also when he catches Josie in the school gym at homecoming.