Will this plug directly into my existing mirror wiring?

Yes. The connector harness matches your factory electrical setup — no splicing or adapter needed. Plug it in and you're live.

Do the mounting bolts come with this mirror?

They do. Everything needed to bolt it on is included — no trip to the hardware store.

Does the heating function work on the same switch as the rear defroster?

The heating element operates independently from your rear defroster. Some vehicles run it on its own button; others may share a climate control switch. Check your vehicle's owner's manual for the exact control method.