Are there any buses or shuttles from LA? Are there any trains?

Yes

Yes, got to look for the connections to ontario. You can also fly to ontario airport and the convention is right down the street.

Yes look for LAX to Ontario Airport for the shuttle and there is a Quick Shuttle that will take you to the convention center from the airport

I believe there is bus service. The metrolink station is nrarby but I'm don't know what line it is.

Yes there is a commuter train or metrolink

You can take the Amtrak train from LA to Ontario Convention Center or Ontario Airport. You can also take buses for the same distance but it will take longer and bus changes. You will need to look into the schedule and The routes.

Yes, but i don't know the bus/shuttle system, you'll have to look into that