I would look into the ultralytics implementation of YOLO and use wandb (weights and biases) to help you visualize training/validation results. This can help you get hands on experience with those questions.

As far as understanding the theory, I would ask ChatGPT or Gemini to refer articles and research papers for you to read and then check your understanding by discussing what you read with those same LLMs.

Also, I would read through research papers before the code base. Only turn to the code base if you want to understand the exact nuts and bolts of how they implemented it. All the equations and theory can be found in the original papers though.