I am knowledgable about working out, let me see if I can help you out. Increasing both strength and flexibility will improve your power potential. Improving strength will allow you of course to put more power on the disc, the faster your hand is moving at the point of release, the farther it will go. Flexibility improvement (stretching) improves your power potential by improving joint range of motion (rom), allowing the muscles and their force to act on the joint for a longer distance.
When developing a strength training workout it's important to start at a basic level and go up from there. Many people start out at too high a level and either get frustrated because they're constantly sore or get injured. It's important to work every muscle group as well, they're all used if the drive is done correctly and it's important also to avoid muscle imbalances. The muscle groups you should be working are the leg muscles, the core muscles, the upper back, chest, shoulder, biceps and triceps.
Start off by working out on 2 nonconsecutive days per week, selecting 1 exercise per muscle group and performing 2 sets. Start out light with a weight that can be performed comfortably for 12-20 reps, it's also important to make sure you're working hard enough to feel the muscles fatique (overload) stop the set somewhere between when the muscle starts to burn and total failure. Make sure your doing the exercise correctly called form, 3 things go into form alignment-varies by the exercise, speed-at least 3 seconds on each phase of the lift, breathing-don't hold your breath, try and breath out on the hard part of the lift. After 2 weeks increase the number of sets per exercise to 3, after 4 weeks add another exercise and perform 2 sets for that execise and progress from there.
Sample basic workout: 2 sets each exercise
Legs: Leg Press
Chest: Machine Chest Press
Back: Front Pulldowns
Shoulders: Machine Shoulder Press
Triceps: Tricep Pushdowns
Biceps: Dumbell Curls
Core: Crunches
After your baseline strength is built up you can start working on the muscles that are used significantly during the drive a little more. The muscles that are most utilitlized are the leg, hip, glutes, core (rotational), shoulders (posterior), and triceps. Other than the triceps many of these muscle groups are under developed in many people, even those who work out. Many people believe in working the forearm to improve grip, but the forearm muscles get plenty of work while exercising other muscle groups.
The final phase of sport-specific fitness is to replicate the motions used in the sport with resistance. An exercise tube is ideal for this, grab one, secure one end, and break down the motions of your drives while using it. Basically just break down the motions for the drive and use the tube to replicate these motions. The "equalizer" is just an exercise tube with a few exercises, sure wish I would of thought of that. For backhand: Start by reaching back with the tube and then rotating the hips and legs do this for 15-20 reps don't move the arm just the hips and legs, then work on pulling the tube across the chest until the elbow's pointed straight out from the body for 15-20 reps, then work on extending the elbow and wrist which is the final motion of the throw.
Of course driving practice and improving your driving form is just as, if not more important, than increasing strength and flexibility for increasing distance.