Get rid of the collar and buy a harness -- they are safer for the dog and will stay on much better.
Go to this thread, entitled "New to the Breeding PRocess"
http://www.yorkietalk.com/forums/sho...ighlight=links and read #3 where all the links are given -- you can continue your study there.
Sell your puppies with spay/neuter contracts or keep them until the vet will safely neuter/spay before you sell them.
Good luck with a safe and smooth delivery and finding homes for the little ones.