A Knave is a jack playing card. I'm not sure the book said what the Knaves responsibilities were. Alice is growing even though she didnt eat or drink anything because she is starting to come out of her dream. As she is coming out of her dream she starts to grow back to her normal size. I don't think there is actually any evidence in Wonderland. Everything else is not normal so why would a court trial be normal. I dont think Alices sister really sees the same thing as Alice does. She just wants Alice to think she is having the same dream as her. Everyone wants Alice to leave because she is growing rather large and starting to knock everything over. Alice is called to the stage to testify because she is a stranger to Wonderland. Wouldn't you want to question a stranger if something went missing. The Knave is accused of stealing the tarts beause he is always lying.