Will this drop into my stock air box without any cutting or drilling?

Yes. This filter mounts at factory air box points — install is straightforward swap, no modifications needed.

Does the red finish need to be sealed or painted over before I install it?

The filter arrives ready to install. If you want to change the color later, you can prime and paint it, but no prep is required out of the box.

Can I clean and reuse this filter, or is it disposable?

This is a replacement filter intended for single use. When airflow drops or the filter loads with dust, replace it with a fresh unit.