I kinda skipped to the end of this one so I apologize for redundancy. I am a physical education major, and while that does not make me an expert in the field by any means, I have learned a thing or two in 5 years of college
. I don't know your body type, experience, or limitations so I'm going to be fairly general. Don't do anything you don't feel comfortable with.
I would recommend focusing on flexibility just as much as strength. You don't throw for big D by having a huge benchpress, just look at that 12 year old Wiggins kid throwing 700 feet. Flexibility will help you in the ability to reach back farther and will greatly reduce your chance of injury. Your muscles have the greatest capacity to stretch when they are warm, so perform a 5 minute low intensity warm up before stretching (once you break a sweat, you're warm.) Also stretch at the end of your workout, you're usually warmest then.
As far as actual work, core strength is key, you might try pull ups for lat work, and a one armed bent over row where you rest your left hand and knee on a bench and hold a dumbbell in your right hand hanging toward the ground. keep your back completely flat, and pull the weight straight up to your chest, its a similar motion to a disc pull. anything else is really up to you, but I would keep balance in my lifts and fitness (cardio) in mind.
You may also consider some balance exercises, which will improve body awareness. If you are kinesthetically aware of your body movements in space, you can more easily manipulate your movements to correct form problems.
Lifting weights shouldn't hurt your game, just keep in mind that with such a light object the velocity is generated mostly by speed, not strength.
