1 & 2 . I assume you may search those flights on BA.com and the fuel fee + tax will be shown once you've selected the specific flight on that.
3. I heard that you may ask for a application form aboard when you're travelling J or F and they will waive the fee for you. But I don't know if that's true or not. You may also apply for a CX AE card to enjoy a free enrollment for the green tier membership