If you would like to go with a kibble diet, I recommend NutriSource, they have a great selection of flavors and all are good for your dog. Most importantly, when looking for a good kibble, look for grain-free. Grain-free feeds will require less food (quantity) per day and be very cost effective when you don't have vet bills. Having that said, some other brands that are pretty good are Taste of the Wild and Merrick (I believe this is sold at Tractor Supply and smaller mom and pop feed stores).
Evaluating a Dog Food - What is Meal Anyway?
When you evaluate a dog food look at the ingredients, in the first five ingredients there should be at least two "named" meats; meaning you want to see "Chicken Meal" or "Salmon", not "Poultry" or "Fish". This insures that you are not getting a bag of left over bits that are otherwise unusable. The difference between Chicken and Chicken Meal is also fairly simple. Chicken Meal is actually better because it has the moisture removed from the feed. When you see Chicken for example, the chicken is included with all it's moisture content (often up to 70% moisture, this means that although the chicken is in the first five ingredients, that actual amount of chicken may be a lot less than it seems because of the water weight. I also look at the rest of the ingredients and, for the most part, you should know what they are, you want to see things like sweet potatoes, not a chemical compound ;-) Again, look for grain free. As far as percentages go, I try to get at least 24% protein (better if 30% or more), no less than 10% fat, ideally 15% or more (the dogs really need a fair amount of fat, I supplemented mine when they were still on kibble with bacon grease and lard, especially in the winter and during hunting season). Also no more than 10%-12% moisture, any more and the food doesn't last as long as has the potential for going bad, plus you're paying for water. I recommend storing kibble in a food container with airtight seal so that it stays fresh, otherwise an opened bag starts losing flavor in 7 days or so.
Evaluating a Dog Food - Protein
You can also evaluate a dog food based on how the feed derives its protein and fat. More expensive, and better for your dog, feeds will use animal-sourced meats, like beef, chicken, and salmon, while lesser meats will use plant-based proteins. Plant-based proteins will be seen in the ingredients as Pea Protein or Soybean Meal. Protein from animal sources is generally more bio-available, meaning your dog can actually use it. Plant-based proteins are not necessarily complete in their amino acid profiles, nor can dogs get all the protein sourced from them. Feeds with lots of plant-based protein are of lower quality because they artificially raise the percentage of protein in the feed since your dog probably can't use it. Most dog foods tend to have a few different varieties and they will change the protein and fat percentages. For GSPs, because of their high metabolism and energy level, I try to find higher protein and higher fat. I feed my dogs the NutriSource Grain-Free Lamb Meal because it is at 28% Protein and 18% Fat, whereas some other varieties are at 25% Protein and 15% Fat.
Evaluating a Dog Food - Fat
The same works for fat in the dog food. Dogs need fat in order to maintain proper fitness and health. I find the amount of fat your dog needs depends on his age, health, activity level, and climate. GSPs tend to have higher metabolisms and therefore need more fat. I shoot for at least 16% fat in my dry dog foods, often more for my GSPs, where my mutt would be fine with a lot less.
Having that said, it is very difficult to find dog feeds that don't have any plant-based proteins or plant-based fats, the important thing to take away is whether the majority of protein and fat are derived from plants or animals.
As far as treats go, I highly recommend chicken feet, I know it sounds gross, but chicken feet (found in the meat section of some groceries) are very high in naturally occurring glucosamine and chondroitin and these are very helpful for their growing joints as a puppy and maintaining joint health as an adult. I try to feed mine one a day, but you just find a schedule that works for you.
For training, find something that is small that you can get in bulk, I like the Pet Botanics since you can get a million treats for a few bucks, just keep the bag sealed because if they dry out, the dogs lose interest. I do prefer positive reinforcement for training over treats, but with puppies, or any dog, you often need a little food incentive to get the ball rolling. GSPs, although a bit stubborn, are not terribly difficult dogs, they respond well to firm, consistent training, changing your tone is generally all that's needed to correct an action.
Other treats are the occasional leftovers (no cooked bones, please), eggs (raw and the shell, too, if they will eat it), peanut butter (a scoop put in a kong or licked off a spoon), and cheese (I just say cheese and my dogs run to the fridge). As far as treats from the store, whatever you like to buy is fine. I try to stay away from chemical things l don't understand the ingredients on. Rawhide is generally fine, there are some concerns with choking or blockages, but these are very rare and I wouldn't use it as an excuse to never give them to a dog, one piece a day wouldn't be dangerous.
If you are concerned about cleaning teeth, rawhide can help, Greenies are good, too, but if you want a cheaper alternative, raw chicken bones are great, again, these can usually be bought in the meat section, they should be under $.50/lb.
With toys I try to stay away from plastics, they seem to always get torn up and ingested, I do love the stuffingless rabbits, coons, and foxes with the squeekers, my dogs love tennis balls and playing fetch, I use the Chuck It! arm to throw it farther because I grew up playing soccer, not baseball, and I am terrible at throwing and these dogs can run far. Again, rawhide bones or femur bones are great additions here. All large-mammal weight-bearing bones, like cow femurs, are best as treats and not a part of a diet. As a special note for bird dogs, try to steer clear of the game of tug-of-war, nothing is more disappointing than having your dog point and retrieve only to tear your bird in two when you try to get it from his mouth.
Ultimately how you feed your dog and what treats you buy are your choices to make, I'm not going to judge people's decisions, my job is to educate those who want to learn.