Do I need to remove the entire mirror housing to swap the glass?

Yes. You'll need to unbolt the mirror from the door, then disassemble the housing to access the glass. Once the housing is off, swapping the lens is straightforward—most drivers finish in under 30 minutes with basic hand tools.

Is this pre-assembled or do I need to install it into a housing?

This is the glass lens only. If your current mirror housing is intact and undamaged, this lens swaps directly into it. If the housing is cracked or broken, you'll need a full mirror assembly instead.

Will this work if my mirror has a heating element?

This is a glass replacement—heating function (if equipped on your vehicle) remains in the original housing. Confirm that your housing bracket and clips are still good before ordering, since a damaged housing won't hold a new lens.