You are thinking about it backwards. Of course first there were only animals who couldn't hibernate, and who couldn't fly (for example single cell life forms...). It's not as if god dropped some bears into Canada and then when winter came they suddenly had to evolve the ability to hibernate.
Why don't you go grab a book about evolution theory that explains all those things?
I don't know how long it took to evolve flight, but it doesn't really matter. I could guess: flying underwater is a lot easier than in air, because you can drift even if your wings (fins) don't really help you control your direction much.
The first animals that could fly above land probably couldn't fly like today's birds either. Perhaps they could only drift a little while jumping from a tree. Or perhaps they were tiny animals that could actually float in the air (on a smaller scale it works), so that forming half working wings was some advantage already. The reality is probably something else, as I said, I don't really know.
You could pose billions of questions of that kind about evolution (why did animals evolve to do this and that, and how). Just because a random evolutionist can't answer every such question doesn't mean it is wrong. It just means you have to look up the answer yourself, or research it yourself. Biology is not a finished field of research.