There is a big difference between saying something is possible and saying something is easy. I don't think it is easy to build a moon colony. On the other hand, I do not see any scientific or engineering reason why it is not possible. We have already proven we can land on the moon and that we can build space colonies (i.e. ISS). Sure there are hurdles I have not considered, but that just makes it hard not impossible.
2. I bet we could figure it out. Again don't see any reason why it is not possible. Very little research has gone into that particular problem which I think is the main reason it has not been done.