Your plan sounds very good Ali!
I'd say go for it
Yes, it's a good idea to feed organs at least twice a week. If your pup won't eat raw liver or kidney, you can always brown the outside of the meat a little in a pan (make sure you never, ever cook any bones though! Cooked bones can be really dangerous if ingested).
Since your boy is still growing, you could even add organs to 3 or 4 of his meals a week (a little at a time to avoid diarrhea).
Don't worry so much!! I promise you, you will not mess him up
You'll be making him so much healthier with this new diet. You must feel better already not to have to give him the nasty ingredients from the prescription diet, right?
Think of it this way; do you calculate, weigh and figure out ratios for your own meals? Did your parents balance out every single meal you ever ate growing up? And yet, you turned out just fine and healthy, like everyone else does.
Many people do weigh each and every meal their dog gets. I personally have always "eyeballed" the portions.
I guess I can point out 3 important guidelines for raw feeding to help you stay on track:
1) Focus on the dog's physical condition. Whatever weights, ratios etc. you're using on food, your dog's body will tell you if he needs more or less food. Ideally, you should be able to see just a hint of rib on him (and be able to feel the ribs easily), but the ribs shouldn't be sticking out too much.
Adjust the meal portions to keep him fit - you can easily tell if he starts to get fat or too skinny and this is a much more relevant measure than weighing his meals.
2) Check the poops daily to make sure you aren't giving too much bone. Again, if the poops are brown or white, you're fine.
If the poops become YELLOW and very powdery (you can't miss this), then immediately reduce the bones you're feeding and add more meats.
3) Variety. The dog's body will extract everything it needs from whatever you feed it (just like our bodies do). Make sure you don't end up feeding nothing but chicken and hamburger for months on end.
Try to include as much variety as you can for the meats and organs. If you can find 3-4 different animal meats/organs to feed and you rotate them around, you'll be fine. This includes raw fish like sardines and mackarel (you can use canned, but raw is much more beneficial).
I think you're being very smart about researching all this before making the switch. You should always be comfortable with what you're feeding your own dog. No need to feel pressured by us - we get very enthusiastic about raw feeding because it's done such wonders for our dog's health, but this is your dog, and only you can decide what's right for him.
After a couple of weeks, once you start feeling more confident about the raw diet, you can always start reading up on some of the veggie and supplement threads. Then you can decide for yourself if you want to add in any "extras".
Some of the recommended supplements are salmon oil, vitamin E and vitamin C. If you buy those at a human pharmacy, you can get them far far far cheaper (and better quality) than anything intended for pets
Best of luck. Please keep us updated on your progress with your pup! I'm sure it'll help out other new raw feeders who are probably going through the same questions and worries as you are. Hehe.
Yuko