The more toys the better, but rotate them. There is no use in having them all available, the dog will just be bored with 20 toys instead of 5.
You'll want a few hard rubber toys for chewing, some soft toys to fling around and play with, some toys for tug (Tucker likes those long stuffed dog toys from the petsmart commercial), some tennis balls for fetching (Tucker likes the ones that squeak), and a toy or two that you can fill with food to occupy him when he's alone or being super nosy. Tucker can kill most stuffed toys, but they sell the ones without stuffing now which is nice.
Tucker has a kong but honestly it's not very useful for us. When he was teething he'd chew it a bit but not as much as his nylabones. You can put food in them but not a whole lot and not a large variety, soft foods like peanut butter and yogurt work well but Tuck doesn't like PB and the yogurt gets eaten super fast unless it's frozen which requires us to think ahead, not something we are great at lol. I got him one of these:
Starmark Fun Ball Dog Toy - Toys - Dog - PetSmart for christmas and it's great for filling with treats when he's looking to get into trouble (starts trying to steal things from the table) or is left alone. You can use big treats or small treats depending on how difficult you want to make it. I usually do a combination of both small and large treats (I use a jerky type treat so i can rip it into different sizes) that keep him from getting discouarged while also keeping him busy for a longer time. I love it, he loves it, my cat loves it
You'll find out what your dog likes, each dog has their own preferance. But introduce hard toys early on, I know many dogs who won't TOUCH hard toys because they were not given hard toys. Now they only like stuffed toys, which is limiting.