Hi Pam and welcome to Yorkie Talk. A pre-congratulations on your upcoming litter. I am not an expert as I have had only one litter so far but I have read many, many, many articles on breeding, so I will try to answer your questions.
It is normal for the female to be having the discharge you described, so that is nothing to be concerned about. I'm not sure about the food you are feeding her, I have read and been told to have them on a high quality puppy food from the time you even suspect they are pregnant until after the puppies are weaned. Also, do not give her too much extra calcium (cottage cheese?) before she whelps as this will tell her body that it does not have to make it on its own possibly causing a greater chance for eclampsia (milk fever) in the female
It is great that you have your breeder friend for help and support! Keep in touch here and you will also find a multitude of help from experianced breeders and breeders like me who will try and help the best we know how. There will also be many just to pop in on your puppy thread should you continue updating us, just to offer their moral support.
I for one would love for you to stick around and would also love to see pics of Izzy and her pups when they arrive. Good luck to you!
BTW, here is my favorite website to go to for much helpful information on just about anything to do with breeding....
Canine Reproduction Video and Book on Breeding and Whelping dogs by Debbie Jensen for dog breeders and Whelping Supplies needed to deliver puppies.