Can I suggest that you obtain some Cocker Spaniel breed/guide books, either buy them or borrow them from the library. They are full of useful info from puppyhood, through teens, adults and elderly. Get several and read them all so you get a larger overview.
Are you getting a show type spaniel or a working type??
Please don't dismiss information that you read on here. There are a lot of people on here with various backgrounds relating to Cockers and dogs in general, from pet owners, to groomers, to breeders, to dog handlers, showers, etc, so they do know what they are talking about. The simplest things are often the things that get overlooked and cause the biggest problems. No one is inflable and knows everything......