They look either anodised, or they have clear coat.

Do you have the little tool to hold the back of the chainring bolts? That might be a dealbreaker; sometimes you just can't get the rings off without one.

And what about a crank puller?

I wouldn't paint them, I'd go raw, since paint and even anodising tend to get polished off just above the pedal...

I wouldn't sand them either. If they're painted, I'd use paint stripper and give em a brushed finish with Scotchbrite or a plastic kitchen scourer.

Staying in the kitchen, if it's anodising, I hear oven cleaner gets it off... dunno what kind of state it leaves the surface in though.