Jane, good luck at the club! I hope I didn’t add more confusion to a topic that already has so much to think about. I actually began college studying exercise sciences and took some nutrition, exercise, and excercise planning courses.
You are correct in that BMR is the amount of calories your body theoretically burns just to maintain your current body. The more muscle tone you have, the higher your BMR is because muscles burn more calories.
The best way to burn fat, and keep it off long term, is to do excercises that get you breathing hard for longer periods than 2 minutes. Don’t overdue it if you have any health concerns, but oxygen is what actually burns fat, so moderate excercise that elevates your heart rate and has you breathing a bit harder is what actually burns an animals fat deposits! This of course all goes hand-in-hand with a good diet. But, simply cutting calories is not always a long term solution! I hope this didn’t muddy the waters more! These are the same things I struggle with daily. The diet is hardest for me as well.