At your age I would focus on doing a lot of body weight exercises as well as plyometric work-outs. Do not worry too much about lifting heavy weights. Do abs daily and make sure you do lower back exercises to compliment your abs...back extensions, supermans, etc...
I wouldn't throw bullpens 5 times a week. Doing so will increase chances of arm injuries. Long toss is great, but just like when you pitch make sure you ice after long toss work-outs. Be careful with swinging a heavy bat because your muscle memory may suffer. You should swing a heavy bat, your regular size bat, and a lighter bat...overload/underload workouts to train your muscles to swing faster while gaining strength with a heavy bat.
Hope this helps.
AND KEEP SPRINTING! SPEED KILLS!