If you decide on getting a Yorkie, be sure to buy it from a reputable breeder. All of the Yorkies I've seen were almost impossible to housebreak. Ones that came from some breeders, those breeders NEVER let them outside! So the pups went potty in the house and when they were outside all they did was play!
A lot of puppy millers breed Yorkies. So be careful where you buy one! Here is another website for you to check out:
Yorkshire Terrier club of America
Scroll down towards the bottom of the page and be sure to check out the FAQ page too. You can also click on their Rescue tab.
You must be very consistent in your training. Take the pup to obedience classes! (No matter what breed you get.)
Anyhoo, I would never get a Yorkie and a Corgie! Corgie's are a herding breed and can really hurt a little dog. If you want two dogs, stick with dogs that are simular in size.
Look up all you can for health on any breed you decide on. Also be aware of all health issues, shedding, non shedding, grooming requirements, etc.
Yorkie's are cute little dogs, but I've seen plenty that had to be put down because of temperament problems because the owners spoiled them rotten and they became very aggressive towards people and other animals.
Yorkie's are very Terrier like. (Hence the name Yorkshire Terrier!) They are usually good with other dogs.
I have friends that breed and show their Yorkies. Their dogs never have to have their teeth cleaned and they do all the health checks. They feed their dogs a totally raw diet. They have great teeth and gums right up into old age. (One dog is 15 and she has all her pearly white teeth and is very healthy!)
Keep the little ones safe and get a dog that is at least close to the same size.
Good luck with your search. Let us know what you end up with!
