Can big groups sit together 11 in the group

Yes They do seat close together keep in mind each table is like a old time car and in the back the have special car to accommodate large groups its a really cool experience

the cars only hold up to either 6 or 9 depending on the age of people

They have cars that hold 10 I believe the seats are like benches sideways

I believe the "cars" only hold 4 people. But I'm sure you can request "cars" next to each other. Hope that helped answer your question.

I think you might but worst case if a few different tables maybe needed.