I don't know if you got all the advice you wanted for the treat taking thing, but I tailored some training to a pom who took treats like a shark LOL. His mom is a dog behaviourist who used the "ouch", but that doesn't work, as the dog still got the treat! So what I did was clicker sessions specific to teaching him to be gentle taking food. She had never even thought of clicker training him to learn to take food gently
I would have two pieces of treats in the same hand, one between my thumb and forefinger, and one in closed in my palm and the other 3 fingers. clicker in my other hand. I would hold the treat out that was pinched in my thumb and forefinger, and wait until he tried taking it gently. if he grabbed, I would pull it back, wait a couple of seconds, then try again (I did wear leather gloves the first session, btw lol) when he finally took the treat gently, he go a click then I opened the hand for the other treat, feeding like a horse, so he didn't bite when he grabbed that one. The first treat is NOT the reward for the click, the second one is, so he learned that taking food gently got him a second reward.
I told my friend not to hand him treats for awhile, when working on anything else, but to toss them on the floor, so he couldn't revert to his old behaviour until he was solid on the "gentle"
He now is a perfect gentleman after 5 years of grabbing fingers along with food