BREATHING RATE: "Every 2" vs. "Every 3"

[Alex-SG]

After months of drilling, I'd like to start focusing on the breathing part + swimming.

At this time I can swim 100m max and then I am out of breath. My goal is to swim a MILE in 32-33min in bilateral breathing

1. Shall I go straight to Bi-lateral breathing (every 3) or start "every 2" and then move to "Bilateral"?

2. What is a target BR = Breathing Rate ("1 breath every X sec") for a long distance, relaxed, 32min Mile swim?

3. Assuming BR is a constant, does this mean the SR (Stroke Rate) for the swimmer has to be faster when breathing "every 3" vs "every 2"?

Thanks in advance for your views on this. ALEX