I'd like to recommend the books in the deathgate cycle to you, by Margeret Weis and Tracy Hickman. Also Spelljammer Cloakmaster Cycle if they are still available (several authors, can't remember who they were but the first book is called "beyond the moons")

They should tickle your imagination... If you like fantasy and/or SF.

not sure if this is right but if the world was inside out, would gravity still force us downward so everything would be forced into the center of the world, which would mean everything would be a giant clusterfuck in the sky?

If the earth were hollow but still the same mass then everything on the inside would be pulled toward the shell, even if there was enough air to fill up the center it would be really dark

Not if it were hollow, which would remove most of the Earth's mass, and without all of that mass, the gravitational pull would not pull towards the center, and with its orbit, it would push us to the flipped ground, much llike the spacestation