Since you're about to take the MSF, remember one thing:
That course is designed to teach you lowest-common-denominator techniques that will keep you safe when all your cognitive abilities go out the window. Which they will in an emergency, and far more readily if you're inexperienced. It's only natural. You've already shared your experiences of getting a bit flustered in traffic. Think about what that's doing to your cognition. It'll all pass with more seat time.
That does NOT mean the techniques you learn in the basic course are the only way to do things.
For example, they teach you NOT to cover the brake when you ride. This is because an inexperienced rider, in a panic, will grab that front brake without thinking about subtle things like how much pressure they're applying. More experienced riders routinely cover the front brake because it reduces your reaction time.
Check my right hand... I'm not slowing down here, I'm accelerating out of a turn.
Same deal with the emergency braking in a turn thing. They make it seem as if you will crash if you touch the brake while cornering. They're right... if you brake too hard, which a newbie is likely to do. But you CAN brake while turning once you have more experience.
So for now, listen, learn, do what they say, and stick with the program because it's valuable stuff. Get experience, then build your skills. More advanced training will teach you those more advanced techniques... the basic MSF is not the time or the place.
Note: I've been riding for 29 years. It wasn't until I hit the track two or three years ago that I really started trail braking and understanding how to balance those forces properly. Point is that you can become a safe, successful rider and have a great time following the basic MSF guidelines.