Hi.
That first question is broad! In general, I'd say it is a pretty interesting job, especially if you like solving problems and figuring things out.

Stars can change colors - but only over very long periods of time. In a few billion years, for instance, we expect our Sun to expand into a red giant star - then it will go from being white to - you guessed it - red. Usually, though, they don't change colors quickly.

Sometimes it looks like the Sun changes colors - it looks redder at sunset, for instance. That is because of Earth's atmosphere, though, not a change in the Sun itself.

cheers,
Terry