CONGRATS!! So excited for you! And you must post some piccies when you can.
Yes, an xpen is a great idea for when you can't be with them - we too used something similar when ours were puppies. You sound totally prepared and ready
. Be sure and ask your breeder if she's noticed any hypoglycemia episodes as these are common in yorkie puppies (almost always outgrow them though). If concerned, you can always buy some Nutrical and have it on hand just in case.