I give this advice all of the time...decide what kind of program you want, and then go buy dogs. Easy to find breeding dogs, are easy to find for a reason. Chances are the best are the ones you have to wait for.
When starting, find a mentor that has a program similar to what you want to do. They can help you find the right dogs.
Whether you are starting your program or managing your program, you have to weigh these factors.
Some breeders do none, some do all. How much or how little will depend upon breed and your own personal belief. Do not let one person, even your vet convince you this is required. Find out from multiple people what is actually expected. (FB chat room is perfect place to ask because you will get multiple viewpoints.)
Always remember who gets first pick of any litter!
Congenital Defects can present in any way that makes the puppy unviable. Missing Body Parts, Deformed Body Parts, Water Baby, Parrot Mouth are all examples of things that are Congenital.