I have a male veiled chameleon who now exclusively eats from my hand. It's a pain, really : P
At first he wasn't quite so cool with it, though I just remember offering him crickets, I don't think I ever food deprived him to get him more interested in the project. He started by eating a cricket or maybe two from my hand (I'd hold them by a back leg in front of him), then eventually a switch flipped and he started cowing down and eating until he was full. Now even if I hold a cup of crickets in front of him he's not interested, then if I take the same cricket out and show it to him he eats it...
So, your questions, I'd skip the tongs if you're trying to make your chameleon more tame, otherwise it's user preference. I have no elevation tricks in terms of holding the crickets in front of him, though I guess they tend to be a little below him because he's usually high in his cage and I don't want to hold them above him and tempt him to shoot towards lights. As for the range, I guess it tends to be maybe 5 inches? Sometimes he isn't paying attention or something so I take the cricket and actually touch his mouth with it. Then he looks and I draw back and he's interested.