Yes, the stool sounds normal. If it gets white and chalky, that would be too much bone. If you do give liver a bit later in the course of things... just give a very teeny, tiny amount or he may get really runny poo.
Their bodies do not utilize alot of the things in other diets... hence more poo.
Yes, there is no need to hurry onto another meat. Chicken breast is good too, for starting on because it has more meat and the bone is easy to chew.
Congrats on the new pup!