The cups generally are not available as spares, even if you could get the old ones out.
Cones are usually available, but there are many different versions for different hubs. Usually they differ in the sealing arrangement, but they can also differ in the contact angle. It can also be the case that the cost isn't far off a complete hub.
If you swap the balls for new ones, use loose balls that all come from the same packet. If you are replacing caged balls the correct number is one fewer than as many as will fit in. Caged balls are used because they are easier for fast assembly, not because they are better.