If the rumors are to be believed, the current keyboard is no longer shipping, so that would indicate the answer is 'yes.' With that said, we don't really know
Yes. The new keyboard would replace the Apple keyboard. I hope they also make a matching mouse to go along side. The mighty mouse is OK, but I'd like something new. Maybe they'll announce the rumored "Multi-touch mouse".
I hope they continue to sell the current keyboards - I love them. I don't think I'd like a slim keyboard - I don't care for the MacBook keyboard all that much, so doubt the new keyboard will be all that great for me