Looking for new routine

[MyWeightsAndI]

Looking to get serious about bodybuilding, but I have some questions on how to transition from my current bro split to a better routine.

1. I currently take a class in my sixth period (Junior in high school) which focuses on weight training. The split goes like this:

Monday: Bench
Tuesday: Squats
Wednesday: Cleans & Deadlifts (Can pick between one or the other, or do both)
Thursday: Bench
Friday: Squats

Our coach also seems to "mix up" the routine (It randomly changed from Squat, Bench, C/D, Bench, Squat to the current routine). How can I balance my powerlifting/new gym routine around this?

2. I've been following a bro split for seven months now (Pretty much ever since I started lifting). The split goes like this:

Monday: Chest, Shoulders, Abs, 25 min cardio
Tuesday: Legs,
Wednesday: Back, Abs, 25 min cardio
Thursday: Arms,
Friday: (I usually don't go on Fridays, but when I do) Legs, Abs, 25 min cardio

3. What kind of gains can I expect to make on a different routine? Where should I go to find the best new routine?

4. How should I do my cardio?

Background info:

16 yo, 5'9, 136lb

Bench: 155x1
Squat: 215x1
Deadlift: (Untrained)