1) Wow, I only learned just now that you can have an animal in a stable not in your pasture:
Page 7: "Each stable outside of a pasture can hold exactly one animal."
I believe #2 answers #1. Because you can move animals at anytime, you may either keep the animal there or move it to another pasture.
Page 10: "You may redistribute the animals on your farm at any time to make better use of the space in your stables and pastures (see page 7). Just make sure all of your animals are accommodated afterward, or they will run away."