Good Luck with your new babies! Chihuahua's are so cute...and they know it...My Tinkerbelle has us wrapped right around her little paw.
I started her out with a cat harness and lease...they are lighter weight than anything for a dog. We alway take her outside. We have hawks around here as well as crows and other wild things...I figure that they won't bother her if they see a human with the dog. We also praise for a job well done.
I have a piddle pad under my dining room table for emergency use.
As far as holding them...I sew almost all the time...so didn't have the time to hold our baby dog as long as she would like...so I made her a pouch that I would wear around my neck....she was against my heart and would sleep in there forever. You may have a smallish shopping bag that will go over your head that they will love. Put a small towel in there, too.