Question: What kind of instrument was the bum playing when we first meet him?
Answer: The instrument is called a Hurdy-Gurdy. It is a type of wound string instrument.
Question: When Hero Boy gets back from the toy room in the train, what were all the kids shouting?
Answer: After "Hero Boy" gets back into the train the kids are all laughing and spouting gibberish. This is often done in post-production when backround noise or talking is necessary. They aren't saying or shouting anything in paticular, just a bunch of kids jabbering on about nothing. I listened to that section three times and it's just gibberish.
Question: In the scene at the end where the conductor is finishing stamping everyone's ticket (e.g. know-it-all got 'learn', girl got 'lead', etc), what was on Hero Boy's ticket? I didn't watch the English version and the conductor said not to say it out loud.
Answer: It says "Believe".