Will this plug directly into my existing mirror wiring?

This uses factory connector points, so it should integrate with your vehicle's OEM electrical harness. Confirm your vehicle has the powered mirror wiring package before purchasing — some trims came without it.

Does the heater function independently from the defroster?

The integrated heating element operates as a standalone system — you control it separately through your interior controls. It runs independent of the windshield defroster.

What's the return window if there's a fit issue?

Contact ModSupply directly for return eligibility. Since this is a mirror-specific assembly, test-fit against your current mirror before finalizing installation to confirm alignment and connector compatibility.