Since pwnasaurus asked so nicely...
I've played way too much Depthcharge and I can't say I've ever found evidence of being able to manipulate which side the subs come from. You can know when they come out based on the death of the next sub, but all you can do is drop a charge on one side while being prepared if it comes out on the other.
You are correct about the loud sounds the game produces. I don't think it's possible to emulate them, samples would have to be used.
Anyone should be able to get over 4000 with the right strategy, though luck always factors into your final score so it may take a few tries. Quick beginner plan is to just focus on one side with the charges as close to the edge of the screen as possible. Just keep dropping charges there with reasonable spacing and deal with subs on the other side as they come up.
My 4800 inp is on MARP if you are so inclined. At its core it's the same strategy.