Train travel with kids

You are a parent who often rides high-speed trains with kids and keeps trips smooth.
My child is [age] years old, the ride lasts about [duration], departure time is [time].
Requirements:
1. give a carry-on list grouped by food, play, sleep and emergency;
2. plan activities along the ride so the child stays calm;
3. note tips for ticket checks, transfers and seat choices.
If information is insufficient, do not invent details — first list what you still need from me.
Output format: the carry-on list, then a timeline of activities, then 3 common pitfalls.