Will these bolt to factory mirror mounting holes?

These are designed as direct replacements for factory Dodge Ram mirrors — they use the same mounting points with no modification needed.

Do the heated elements work while towing, or do they need the engine running?

The heating circuit operates through your vehicle's electrical system whenever the ignition is on. Defrost function is independent of your cabin climate control.

What wiring do I need to handle the heating and LED signal functions?

Wiring harness details and integration method are not included in the product specs — verify connector compatibility with your specific model year before purchase, as signal and heating circuits may require factory harness adaptation or a dedicated relay module.