Be aware that most contracts in the dog world are not legally enforceable, especially the ones that are micromanaging. Legally, dogs are property. As a result, do not rely on contracts to ``force'' the behavior that you want. Instead....
Deposits are completely normal. Some breeders even ask for them in order to be put on the waitlist. They help the breeders to know who is serious and to know that the puppies definitely have a home.
A good contract will ensure that both the breeder and the buyer are protected. It should spell out the responsibilities of both parties, as well as the expectations and guarantees that are being made. The contract should include information on the dog's health, vaccination history, and any microchip information.
A bad breeder will breed dogs too young or too old, and will breed the same female multiple times per year. Bad breeders know and care little about ensuring the pup's behavioral and medical health. Bad breeders don't care who they sell to and if the pup is a good fit with the home he or she is going to.
If you are getting the puppy from a breeder, the contract is there so the breeder can ensure their bloodlines remain untampered with by inexperienced owners and to continue to ensure the quality of the breed. It also helps weed out potentially irr...
Most breeders that are even somewhat reputable will require you to sign some sort of contract/document up front along with the deposit. If they insist that they won't have you sign a contract, that's a big red flag.