Yes. You must.
Only if they have a residential address in Canada.
I had a Norwegian buddy in college who owned a Honda, and every illegal immigrant can buy a car. Cars aren't restricted to US nationals.
No, just the child.
A non-citzen can become a citizen in the US if they follow the proper procedures.
Vote.
A citizen can petition their parents if the citizen is at least 21.
No visa is required to buy property but to enter the US, you would need at least a b-2 visitors visa.
obviously not
Not legally.
Yes. Much of the real property in the United States is owned by non-citizens.
Marriage is a wonderful event. Yes, if a female US citizen legally marries a non US citizen in the state of Michigan, they are indeed legally married.