The term 'aliens' implies a civilization of lifeforms as advanced as us.
Sadly, there is NO evidence that there are others like us inhabiting the universe.
I think so. And personally, I think they would look almost exactly like us (If they were carbon-based.)
Think about it, Karas: Bipedal, advanced encephalization, a lack of unnecessary hair. It's very likely, IMO, that exobiological studies would yield something almost mammalian in nature.
Read this:
http://en.wikipedia.org/wiki/Alternative_biochemistry
It's possible that their habitat would not experience the same cataclysmic events the Earth has in the past. They might be insects, or reptiles, sure. But these forms are not nearly as advanced as we are.
You have to understand that most 'morals' stem from our own biology.
Hope this helps.