dogs normally won't let it go to waste
.. mine would inhale every scrap and look for more.. then come over and burp in my face
since every dog is different start out slow with the raw.. offer a little as a snack for a day.. then two snacks the next day.. let their system get used to it
after a few days start replacing a portion of their regular food with the raw.. until you are either feeding only raw or a mix of raw and commercial that you intend to feed.. then watch your dog's weight.. active dogs will need more than older lazy dogs and pups will need more as they grow.. so there isn't really a 'set in stone" amount since like horses dogs all utilize their food differently.
Once you have been feeding it for a week or so check your dog's ribs.. if you can feel them but not see them then he's on track.. check every week (once or twice a week) for a good month or two and adjust food as needed.
you can feed beef.. but see how your dog does.. some dogs end up with some really wicked gas from too much beef and beef organs.. and IF your dog has allergies you may want to be careful with the beef.. some dogs are more sensitive to it than others. We used to have a black lab that could NOT have beef in her food.. the gas would chase you out of the room.. and if she had any beef heart or liver she would have to spend the next week outside because of the "doggy diarrhea"
as for the fish.. I'm not sure since I don't have access to a lot of raw fish