As far as bus goes, it depends on how you hit it. When we walk up and the bus is just loading it only takes about 15 minutes to get to MK and then another 5-7 to walk to the Contemporary. But, if you hit the bus wrong it could add another 20-25 miutes on the trip. Animal Kingdom lodge sits very close to the AK and Contemporary right by Magic Kingdom. So, if you look at a map of DW and find those two parks you get a good idea of where they are located.
Also, we've taken a cab over which was about $10 or so and it was very quick. Depends on whether you have a car there ... or not. We typically do not.