I too would just paint the pipes. Don't think it's very realistic to replace them.
No big deal to change a skylight. It's nothing more than a plastic dome with face screws right down through the roof.....
and a secondary inside dome screwed to the ceiling inside with a trim flange around it.
I took mine apart, and replaced it when I had the roof done. I ordered the part but they did the install. Still I took it apart so I saw what was involved.
You can take the inside trim ring off easy enough to see for yourself.
Look for youtube videos on changing roof vents or installing fantastic fans or maxxair fans. It'll give you a good idea of what's involved. You might even find a vid of a skylight replacement, but i think the fans are more common and therefore more likely to find a good one.
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