Here's the Cliff Notes version of my question for those who don't feel like reading. For the longer version with more detailed questions, read the post that follows.
1) How many times per week should I train my smaller muscles like forearms, calves, and trapezius (traps)?
2) How many different exercises I should do for each body part?
3) Is there an ideal range of sets and reps?
Don't know if this matters, but just in case: I am 6'2", 200 lbs with less than 10% body fat. I've been working out regularly for most of the past decade, so I have a fairly advanced workout routine and my body is used to physical exertion/lifting multiple times per week. But I'm wondering if I should shake things up, especially since my forearms/calves/traps are really stubborn when it comes to growth.
Also, my overall fitness goal is to steadily keep putting on lean muscle without getting too bulky. Ideally, I'd like to gain another 12-15 pounds of muscle.