Wow this could be a very long response if I'm not careful.
I start with tee work. Long tee (hitting the ball the length of the cage). This is handy for stretching out and getting loose, but these should still be quality reps. By the end he should be hitting line drives to the back of the cage. I have kids aim for the oppo corner most of the time.
Next we work front toss. 15 feet or so tops. This is a good time to isolate problems and work on fixes. Sometimes we use thundersticks and golf wiffle balls to mix it up. Sometimes we move the L-screen to the oppo side and toss at an angle. Sometimes we bounce the ball in to mix up timing. Front toss is probably my favorite thing to do. Lots of options.
BP I would throw from up to 55 feet based on your ability. If the farthest back you can pound the strike zone is 40 feet than do that. Nothing makes it harder to get quality reps than 1 strike for every 10 throws.
As far as the rounds, again, there are a ton of options. We never take more than 10 swings in a round. I've found kids tire and can develop or reinforce bad habits.
We do a 4-3-2-1 BP. 1st round is 4 swings with an 0-0 count. Next is 3 swings with a 2-0/3-1 count. 2 swings with a 2 strike count. And last is 1 swing with a runner at 3b and less than 2 outs.
We also do a "routine" BP. I'm a big believer in an in-box routine between pitches. In this BP they do step out after every swing, go thru whatever their routine is, and get back in. Slower and a little more focused. Fewer swings per round, but I've found it beneficial.
As long as you have a plan for every round or swing you'll be fine. I'm a big believer in fewer but more focused swings these days. I like kids to get to be able to feel every swing so they can make adjustments themselves when needed. 100 focused and thought about swings is better than 250 with no learning process.