Hello and welcome! I'm new here as well!
He sounds like a really smart and well trained dog to me. Perhaps he was a police dog? I often hear that their dogs are trained with German commands.
I was wondering how did you find out that he knows German and attack commands? Did the rescue notify you or did you just randomly say things and he did it?
If it were me introducing my dog to a new person I would not make a huge deal about it because I believe that the dog can sense this and if you are excited or nervous you will make the dog excited and nervous. Just remain calm and allow the dog to come to your husband and sniff him. It would be best if your husband doesn't stare directly at the dog because the dog might think that it is a challenge.
I to, love to look at the ingredients in my pet and people food! It might be because my sister is learning to be a nutritionist. I used to make my dog a doggie stew with mince, beef stock for flavour, rice/noodles, kidney beans, carrots, peas, and silver beat. I would often feed him raw meats as well such as lamb, beef and chicken. I once gave him horse meat but it gave him diarrhea! It's funny because I know of other dogs who are just fine with it. I would also feed my dog kangaroo after we went hunting. He just loved
chewing on a kangaroo leg and tail!