I got past the ghost house and the museum, and now I'm in the castle, but I can't figure out what to do next. Also, what's the point of these light bombs? They don't seem to do anything but give me siezures.

Lightbombs can stop machines from moving.

In the castle just keep going solving puzzles. At the museum get that giant battery in the second floor and use it near the Roller Coaster. Game's most amazing part awaits you.

Yeah, I got that part already. You just gave me the answer to what I already fisnished and told me the obvious part of what I'm stuck on.  

If you're talking about the part with all the Elemental Knight statues, try this, you'll have to scroll down to find the solution but I'm pretty sure that's how I figured it out (after trying the logical routes of placement and failing).

Could you post a screenshot of where ou are?
At the Elemental Knights statues, just think of their elements and colors (red for Fire, blue for Ice...)