Do I need a wiring harness adapter or will this plug directly in?

This assembly comes with the factory harness and connects straight to the OEM door module connector. No adapter needed—plug and play.

Will the power folding work if my car doesn't have that feature from the factory?

The motor is built in, but the folding function requires your vehicle's door control module to support the command. If your 3 didn't come with powered fold, the mirror will function as a powered unit but won't auto-retract.

Does this come with the mounting bolts and clips?

The bracket is included. Fasteners and any clips needed for your specific door panel configuration should be sourced separately—door designs vary by trim level, so have a parts diagram handy before install.