Welcome to BPO!!! Your Mal is BEAUTIFUL!!! I have a GSD that is about 10mths old she is going through her second fear stage. I took her to a dog event in town and at first she was terrified at all the noises, etc (she had never been afraid of this before). I just ignored her behavior, acted calm, and began walking around, I walked around kind of a distance away and then moved her closer to all the action. By the time we left she had a ton of people love on her, been smelled up and down by every different dog you can think of, saw some horses, and walked under a big rig that was there!!! So there is hope!!! He's young, and he'll come around, just give him some time since you haven't had him through all of puppyhood!
Issy also gobbled her food when I first brought her home, she was 4mths and had been in a shelter. Now, she's my slowest eater!!! She even eats laying down!! I would definitely look into what other foods to maybe feed but I wouldn't worry about how he eats at the moment, just the fact that he's eating is good!!! Good luck!