Will this fit into my existing mirror housing without any cutting or drilling?

Yes. This lens is designed to mount directly into factory mirror points. No modification to your current assembly needed.

Do I need to remove the entire mirror from the door to swap out the glass?

You can remove just the glass from the housing without taking the whole mirror off the door. The exact removal method depends on how your specific mirror assembly is held together — test-fit before committing.

What condition is the glass in when it arrives?

The lens ships clean and ready to install. Inspect it before mounting to confirm no damage occurred in transit, and wipe it down before final install.