If I had a polished wheel and wanted to paint a portion of the wheel. Would it be best to:

Paint it and clear coat the wheel

or

Powder coat the wheel and clear coat it(or is clear coating necessary when powder coating)?

If it was me I would take a red scuff pad to what you want painted and hit it with a good single stage or even a good coat of spray paint, Mainly because I don't know how well a clear will stick to polished aluminum. If you rattle can it a adhesion promoter would probably be a good idea.

Don't clear over the polished part.

powdercoat the rims. spray painting will work but eventually it will peel no matter what you do