Can we get rid of the notion of Hollow Earth?

Oh, and a few more things... if the hollow earth theory is correct, explain to me these "minor" details:

1) How can we explain how much we weigh? We know the mass of earth, moon, and other planets. We know what we weigh on the earth and the moon and can calculate how much we would weigh on other planets. With the exception of a sun being located in the middle of the earth, how would you explain our relative weights?

2) A slowly moving core gives reason to why certain phenomena occur, in weather patterns, and in your toilet. How would your toilet water flush in one direction on one hemisphere, and the opposite direction on the other hemisphere if we didn't have a slowly moving core? Again, explain this without saying that we have a sun in the middle of the earth.

Thank you.