DL, Squat and Bench
Lift, Eat and Sleep
That's really all there is to it. Make sure he's doing the lifts properly, eating enough and sleeping enough and the rest is just time.
I think whoever told you that was saying to give those priority, which I agree with. In addition I'd also prioritize dips and pullups. That said there's nothing wrong with doing the curls, the calf raises etc. once you've done what you need to do on the big lifts. It's been mentioned already but...
My chest routine is bench, db press, dips and flys. Of those I noticed the most difference after doing dips for a few months, my chest filled out and I did receive comments on it.
I am in a similar situation, my body doesn't seem to like bb bench but loves db bench. You say you're up to three plates, what do you do for the amount of reps on db press?
I tore my acl and dislocated my knee about three years ago and squats are one of my favorite things to do (along with deadlifts, dips and db press). As has been said they are key to developing the rest of your body. I have found that if you keep the fundamentals in mind (proper form, warm up...
I have found that to be true, I was 350lbs at one point and now am 250ish and a fairly solid lifter with 19" calves. I will admit genetics plays a role in it but so does my workout; which is four sets of reps until I can't stand the burning with six plates on the calf raise machine twice a week...