For the first thing, yes - with some difficulty. By focusing on the chemical and mineral makeup of the metal, it may be possible to change the colour, but generally only to the colour of other types of metal or minerals. This might be better done by having the character cooperate with a light user, or something similar, since it's easier for other magic to accomplish a better effect. But in short, yes, doable with a lot of effort (unless you can be imaginative and convince us and the other players how it makes better sense).

As for the second thing - actually, a jetpack scooter should be fine! The game is pretty full of weird stuff as-is, so it probably won't give much unfair advantage. Also, be aware that technokinetics may be able to use their magic on it in a variety of ways. It's most certainly within game boundaries.