Oh! YOU are Murder, I just responded to your post below, and didn't put two and two together!
He is a really beautiful Normal, also know as Carolinas or Classics. He may be a bit on the thin side, I have two Normals, one is about 100g (named Richard, I love human names for pets!) and one just hit it out of the park at over 1000g! Get a kitchen digital scale and weigh him, that will help you know what size mice he needs. Probably one adult every 10-14 days, but if he is on the thin side you might want to start with something smaller.
Walter looks like he will be happy with you, I think you did a great thing.