Well I try to handle them as much as possible. Especially when feed time is coming so that they can Associate me with positive things. But if you really whant to inprint on them its better just to treat them as a pet bird and just hang out with them on your shoulder and feed them treats.
You need to provide grit when they start eating anything other than chick starter feed. Make sure you use chick grit. Chicken grit is to big until they are at least 12 weeks old. I prefer to offer grit free choice 24 x 7 in it's own container. I do not sprinkle it on their food.
There is no such thing as "too much" handling. The more you handle them the first few weeks the friendlier they will be. I will be getting 25 chicks the first week of April. I am already inviting some of my 10 year old daughter's friends over to handle them. They are all responsible kids but still will only be allowed to handle the chicks with close adult supervision.