Will this bolt up to my factory mirror mounting points?

Yes. This mirror is designed for OE mounting locations — no drilling or bracket fabrication required. You can use your existing fastener holes.

Does the LED side marker need a separate power source or harness?

The LED is integrated into the assembly, but you'll need to confirm the electrical connector type matches your truck's wiring before installation. Test compatibility with your existing harness.

Can I use this mirror with a manual hand crank if the previous owner had power mirrors?

This is a manual mirror. If your truck came with powered mirrors, you'll need to verify that the mounting surface and any trim pieces align properly, since power mirror housings can have a slightly different footprint.