Would there be the possibility of scanning real world animals and the game bringing up a Pokemon that would correlate to said animal eg: I scan my horse and Rapidash appears?
I'm not sure that catching real world animals is what they're going for here. From what Ingress does, where it uses things like statues and landmarks as points of interest, and from what the commercial showed, I would speculate that there will be a home server that decides on a pokemon and it's statistics, and plants a virtual flag on a map that corresponds to it. The phone then picks up on the flag using GPS positioning, and directs you to it. From there, I'd imagine that it would use the phone's camera, speaker, and internal gyroscope to let you interact with the pokemon until it's caught, fainted, or it or you leave, if it didn't just put the pokemon directly onto your phone and let you battle it.
When you think about it, I wonder what it would be like to try to compete with someone to catch the same pokemon. Not like the depiction of the Mewtwo battle, where it seemed that everyone caught it, but, something like a generic Nidoran, that you and someone else both wanted.
No, if they were going to allow for the "capture" of real world animals, there would be an entirely too large influx of Growlithe, Meowth, and Geodude, and frankly, Grimer, Muk, and Trubbish and Garbodor, if they're involved. It could be fun, though, to actually be able to train your favorite pet as a pokemon, like you tried to as a kid.