Yorkies are the sweetes dogs in the world...but you are smart in making sure that you know all of the pros and cons before deciding to buy. I wish that more prospective buyers did their research.
Yorkies (as a rule) ARE NOT easy to potty train. My baby is 6 months...and is still no where near trained. A lot of people on here have 1-year-olds who still have occasional accidents. So if you are expecting a dog that will stop having accidents within a week or two...a yorkie is not it.
Also yorkies are very clingy. Mom and Dad...since your daughter is still somewhat young, I imagine that the yorkie will bond with you more since you will probably be the primary care-takers. So expect your dog to want to be touching you at all times. For example I now do things such as balance my checkbook, pay my bills, and paint my fingernails on my lunchbreak at work because when I am home and sitting down...Sydney is on my lap. She even jumps onto my lap when I am on the toilet (if I don't lock her out of the bathroom)
I just listed the only two cons that I have experienced in yorkie ownership. However the pros are too numerous to name.
Good luck with your decision and please share pictures of your puppy if/when you get one.