1) Yes, I believe you can capture at least something with your smartphone.
There seems to be slow shutter speed apps for iPhone, I just googled a couple and those offer max 15 second shutter speed plus Bulb mode. You will need one of this kind of apps to have long exposure on Aurora Borealis.
To keep your camera still during the long exposure you'll need a tripod with a iPhone suitable head, something like a clamp or a car phone holder.
That's what is needed, if it ever is possible to capture the Northern Lights with an iPhone. Whatever you'll catch with it, you will need some post processing on the photo. That you would best do with a real computer program, but I guess there are nice photo editing apps for iPhone too.
2) No, although you might capture something with colors in the night sky with an iPhone, it would be so much better with a real camera.