Use an eye shadow primer, set the primer with a matte eye shadow that matches your skin tone, then apply the liner and set the liner with a black eye shadow.
No, eyeliner has never been proven to affect eye color. If you got it in your eyes, it could irritate or even damage them but just on the eyelids, it...
You usually only need one or the other. Really it's whatever you like. I personally like primer better, but it is up to you. Try both and see which one...
There are a few ways you might removed stubborn creases. Washing your curtains one (or more) times and immediately ironing them after washing can be effective. Iron slowly and focus...